Hi, my name is Lindsey. I’m a student in North Carolina if you must know. I’ve always been really good at math, those stereotypes about girls aren’t all true. But I never thought it would give me the most intense sexual experience of my life so far. Not that there has been all that much of it so far, I’m only 18. What else should I tell you to introduce myself? I have brown hair. It’s actually curly but I straighten it because I prefer that look. I’ve got full lips (my mouth, you’ve got a dirty mind, you’ll find out about the other ones later).

Anyway, I have this differential calculus course this semester and I’m really struggling with it for some reason. I won’t go into all the details of how my stupid school handles which courses you can progress onto, but I managed to get myself into a situation where I had to get an A on the calculus course. I found the stuff really hard and, to be honest, I didn’t do all that much work and my grade was barely a C. I decided I’d better use my secret weapons and see if I could talk my way into a better grade. My secret weapons? I’ve got 38D breasts. I know, that’s huge. Especially since I’m only 5′ 7″ so they really make me busty. I’d noticed the calculus professor eying them a couple of times so I decided it was time for him to see them close up and I made an appointment to go and see him. First I put on a loose top, no bra underneath. I decided maybe my breasts alone might not be eye-catching enough so I also put on the shortest skirt I owned, along with the teeniest thong in my underwear drawer. I was certainly turning a few heads as I walked across the campus with my breasts swaying. I even felt half-naked since I was wearing so little.

I arrive at the professor’s office. He’s on the phone but he gestures to a chair in front of his desk so I sit down. I don’t think he can see up my skirt from that angle but he’s not really looking at me. He’s looking at his computer screen as he wraps up his phone conversation. Finally he puts down the phone and turns to look at me. Typical man, he looks straight at my breasts, not my eyes. He’s probably got a hard-on already but I can’t see because his desk is in the way. He’s a lot older than me, of course, with a grey beard. Actually he looks a bit like a math professor from central casting. He’s quite attractive. It won’t be a hardship at all if my plan comes to fruition.

“I need to get an A on this course,” I say and tell him why.

“Well, you will need to work a bit harder to bring your grade up,” he says.

I drop my pen on the floor and I lean forward to pick it up. I know he can see straight down my front, can probably see my nipples even. I take my time picking up my pen, letting him enjoy the view. I hope he is starting to see that there might be some upside from improving my grade.

“Isn’t there something else I can do perhaps?” I suggest.

“Such as what?” he asks.

“Such as fucking you,” I think, but of course I don’t say that. Instead, I actually say, “Perhaps I could do you some sort of favor in return for some extra tuition.”

He’s thinking about this. Wondering just what I have in mind, I’m sure. I drop my pen again. This time I lean to one side as I bend over to pick it up, sticking out one of my legs as a sort of counterbalance. Of course he gets a perfect view straight up my skirt to the tiny thong stretched tight over the mound of my pussy.

“What sort of favor did you have in mind?” he asks finally. This guy has a PhD in mathematics and doesn’t seem to understand the deal that I’m offering.

“Whatever you need doing,” I say innocently. Maybe a bit too innocently so I add “I’ll do anything you ask of me.”

“I’ll expect a lot,” he says cryptically. “I’m very demanding.”

What the fuck? Is he signing me up to be his slave or just expecting me to wash his windows perfectly without a streak.

“I think you’ll find I’m very obedient,” I say. Two can make cryptic remarks. Of course I can’t say anything that is too obvious, explicitly offering sex for a good grade could end both our university careers.

“Very well,” he says. “Come to my house at 7 this evening and we’ll see what we can do to improve your grade.”

He writes his address down on a post-it note and gives it to me, before turning back to the screen. The meeting seems to be over. I seem to be on track to getting my grade improved but the conversation has been a bit oblique and I’m not quite sure what the deal really is. I realize my heart is beating hard at the thrill of the unknown. Tonight I’ll get to find out whether I’ve been clear enough.

**

So what to wear for my trip to the professor’s house? I put on some jeans. Really low-cut, of course, but a lot less revealing than my short skirt. I don’t wear any panties. I like the rough feel of the denim seam where it cuts into my sex. A short T-shirt so I’m showing quite a bit of skin. A bra, of course, this time. Stylish without being too overtly sexual.

I ring his doorbell and he lets me into his house. Typical suburban tract home. I realize that it hadn’t occurred to me that he might be married or have kids or anything, but it is obvious once I’m in the house that he doesn’t. You can always tell a place where a man lives alone.

We have a bit of embarrassing small talk and he gets me a glass of wine. It’s something pretty nice, I think, not the usual student stuff. Not that I know much about wine except that it only takes a few glasses to get me really horny. But tonight I hardly even need that. I could feel arousal in my stomach as I walked the few blocks to his house, anticipation at what might happen, the excitement of doing something risky.

“Firstly, Lindsey, I’m not having you calling me professor in my own home. Call me Paul,” he says.

“As you wish,” I say politely.

“Exactly,” Paul continues. “You will promise to do everything that I wish and you will get an A grade.”

“I promise,” I say.

“Very well. You will come here twice a week until the end of the semester.”

“OK,” I say. I was expecting just to fuck him once but if he wants more than one bite at the cherry, as it were, then I’m up for it. Besides, I just promised to do everything he asked so I can hardly say ‘no’ to the very first thing he comes up with.

“You will not have sex with anyone else.”

“OK,” I say. Of course I’ve no intention of keeping that rule, I can hardly tell my boyfriend he’s not getting any for the rest of the semester because I’m fucking one of my professors to get my grade up.

“You will not get an A grade without learning the material. But I’m a professor and you are a student who has promised to do whatever I ask. I think we should be able to get a little calculus into your head without too much problem. But to make sure you have the correct incentive, you will be punished for each question you get wrong when I test you at the end of each session.”

“What kind of punishment?” I demand. This isn’t quite what I expected at all.

“Something painful,” Paul says. “I think perhaps I’ll just cane you the first time. But that won’t be tonight since you didn’t bring any of your books with you. You’ll have to come back tomorrow night.”

I’ve never had a boyfriend who was into anything like this. Maybe I’ll learn something more than calculus from these sessions. I bet you find the idea of me being caned very sexy, bent over with my naked bottom getting a lashing. Surprisingly, I find the idea really sexy too.

Paul just sits there sipping his wine, looking at me. Finally the silence is too much for me.

“Do you want to fuck me?” I ask him. Let’s at least find out the parameters of the deal.

“Only when you want me to.”

“I do want you to.”

“No you don’t. You came here this evening prepared to let me fuck you for an A grade. But you didn’t really want me to. When I say ‘wanting’ I mean lying on your back with your legs spread, desperate for my cock inside you. When you can’t sleep due to desire and even masturbating doesn’t make the itch go away.”

That doesn’t seem very likely. I mean I enjoy fucking my boyfriend but my desire never gets that out of control. It looks like I’ll get an A grade without even having to fuck him. And he’s so arrogant, I’ve just realized, he said ‘when’ I want to fuck him and not ‘if’ I want to fuck him. Like that’s going to happen.

“Right, take off your jeans and lie down on the rug in front of the fire.”

I’ve no idea what’s going on now. First he doesn’t want to fuck me and next it seems he can’t wait. I’d better be obedient, though. I stand up and unbutton my jeans and slip them over my hips. I wiggle my ass and my jeans fall around my ankles and I kick them away.

Paul directs me to lie so that my feet are towards the fire. He gets up. He’s holding a silk scarf in his hand like one of those conjurors about to produce a dove out of nowhere. Instead, however, he ties it over my eyes as a blindfold. Then I feel him putting something around my ankles. I’m not quite sure what since I can’t see but it seems he is tying my legs to something near the fireplace so that they are spread wide. I’ll bet he’s inspecting my pussy. It’s actually pretty sexy lying here like a porn actress. I can feel myself starting to get a bit wet.

Without warning Paul grabs my inner lips. It feels like he is using some medical instrument. This is much kinkier than I thought I was signing up for. He’ll want me in a nurse’s uniform next. Suddenly a jab of pain shoots through my lips as if he’s touched me with something red-hot. He tugs my lips a little and gradually the pain subsides into a more muted throb. He removes the blindfold and goes and sits down and has another sip of wine.

Although my legs are still tied apart my hands are free. I reach between my legs. There is something small and metallic there.

Paul explains. “I knew I couldn’t believe you when you said that you would not have sex with anyone else. So I’ve pierced your lips and put a tiny padlock to lock them together. You should be able to put a tampon in but not a cock.”

Well, I have to say I was guilty as charged. I certainly had no intention of keeping that promise, as you know.

“You may untie your feet and go home now. I expect you here tomorrow at 7 with your calculus books. I will do what I can to make sure you get all your quizzes correct, but, of course, it will bring me great pleasure whenever you do not.”

I’m just opening the door to leave when Paul calls out a one-word final order.

“Shave.”

**

Soon I am back in my dorm room again. Of course the first thing I do is strip naked. It feels odd walking around with a small weight tugging on my lips where it dangles between my thighs. I grab a mirror to look between my legs. It’s not a view I see that regularly, of course. My pussy has quite big inner lips and now there is a small brass padlock with its hasp running through them. I’d wondered before what it might be like to pierce my lips, and I guess I now know. I tentatively push a finger into my vagina. My lips pull a little against the lock. When I try to push two fingers into myself it stretches my lips too wide and is painful. Paul was right, it is not be possible to have sex. At least, not unless I find a new boyfriend with a tiny cock. But I can still masturbate at least.

I move my fingers to my clit. I watch in the mirror as my fingers open up my outer lips a little to expose the little pearl of pleasure nestled there. I start to make small circular strokes as I fantasize about Paul bending me over to cane me but then being unable to resist fucking me. I’ve never watched myself masturbate before, never watched my fingers playing in the pink creases of my sex. I bet you’d like to watch too.

After all the excitement of the earlier part of the evening it doesn’t take long for me to be close to coming. I drop the mirror and start to pinch my nipples as my other hand rubs my clit harder and faster to take me over the top as I imagine Paul’s cock sliding back and forth in my pussy. He pulls out of me and starts to push his cock into my ass. To tell you the truth, I’ve never had anal sex so I’m not sure what it’s like really, but I find the idea incredibly arousing. I am imagining him grinding his cock into my asshole as I finally make myself come.

**

The next day I find it hard to keep my mind on whatever it is I’m trying to do. It keeps thinking about the evening to come, and the lessons that I will have to learn. What was it he said? I won’t get an A unless I learn the material. I open my calculus book and start to work through some of the exercises. I have to keep stopping because my sexuality intrudes into my consciousness. My nipples seem very sensitive today. I take off my shirt and bra and sit topless at my desk. Now I can stroke my breasts and touch my nipples when my body gets too insistent. I force myself to work through the exercises at the end of the first two chapters. Sex and math, who’d have thought that would be a winning combination? Smooth functions and smooth skin. I’m desperately aroused but I’m determined not to masturbate before my lesson this evening. I want to go there already at fever pitch.

It seems to take forever for the clock to advance enough for me to prepare for my lesson with Paul. I take off my clothes ready for my shower. I look at myself in the mirror. Since I’m in a sexual frame of mind my breasts look even larger than normal. I look lower to the triangle of brown hair beneath my belly that will soon be gone. I’ve never shaved before so I’ve not really seen the cleft of my sex since I was a little girl. I go into the shower with a new disposable razor and soon my front is newly mowed. It is harder to shave my outer lips since I can’t see what I’m doing because everything is hidden by the curve of my body. Not to mention there are sensitive folds there that I definitely don’t want to cut. I push a lip away from my thigh and run the razor over the outer edge of the lip. Then the most difficult step, I pull my sex open and run the razor on the inner edge of the lip, taking care to avoid the padlock that fastens my sex. Finally when both lips are done I pull my outer lips up and apart to remove the last bit of hair that nestles at the top of valley between my lips.

When I’m back in front of the mirror I look so different. Above my waist I look so grown up and feminine with my big breasts. My first thoughts are that below the waist I look like a young girl. I didn’t think you could be more naked than simply taking off your clothes, but without the modest shadow of my pubic hair it is easy to see the pink beginnings of my pussy nestling between my marble-smooth lips making me look more sexual than normal. And when I move my legs apart a little I can see the brass padlock hanging between my thighs, swaying slightly when I move. I bet you are picturing my naked body in your mind.

I’ve just realized that Paul has not seen my breasts yet, apart from a quick glance down my top when I met him in his office. I imagine his hands on them as I reach up and caress myself, pinching the nipples until they are hard. They seem to have a direct connection to my pussy today, I can feel myself getting wet. I glance at the clock and I realize that it is getting late. I already laid out the clothes I chose for this evening on my bed. I put on a bra, a skirt and a silk shirt. An elegant look, not too overtly sexy, don’t you think. I’m about to put on the thong I chose when I decide to be even more daring wear nothing underneath my skirt.

As I walk to the professor’s house it feels like everyone can my sex. I’ve never gone out before in a skirt with no underwear. The slightest breeze that disturbs my skirt makes me worry that it’s blowing it up over my head like that famous picture of Marilyn Monroe. And my bald sex makes me feel even more exposed and vulnerable.

Soon I am in Paul’s living room, talking about the weather casually as he pours me another glass of wine. For the next hour we sit and go over the first few chapters of the calculus book without the slightest hint that we are co-conspirators in a sexual liaison. He doesn’t flirt or make sexual remarks. He doesn’t try to ‘accidentally’ touch my breasts or my ass like many men do. He doesn’t try and look up my skirt. I’m wondering if he has changed his mind on our deal. Then I feel the padlock between my thighs and I feel a shiver of sexual anticipation and I know that something will happen.

Paul produces a sheet of paper with 10 questions on.

“Work through these questions,” he tells me as he takes my wineglass and walks across the room to refill it.

The first 5 questions are easy. I’m pleased that I’m actually learning something. In math you can be pretty certain when you have a question correct, apart from silly mistakes anyway. I worry that perhaps I’ll get them all correct, in which case I won’t need any punishment and for some reason I know that I want to be punished. The last 5 questions are harder and now I’m sure I have got several wrong. I can feel the thrill already starting to flutter in my stomach.

Paul returns with my wine glass and I notice that he has a birch cane in his hand now. He picks the sheet of paper where I have written my answers.

“Three strokes of the cane for each wrong answer,” he declares. “Go and bend over that chair there.”

He points to an easy chair. I stand in front of it and bend forward, pressing my breasts into the seat, leaving my bottom sticking up in the air. I feel Paul lift up my skirt, discovering that I have foregone underwear. My pussy feels very exposed too, but somehow I don’t mind and, in fact, I find that I have moved my feet apart a little like a mare on heat presenting to a stallion. It’s as if I can feel Paul’s eyes wandering over my lips and my ass. I can feel myself starting to get wet with the attention.

“No thong today,” Paul says approvingly. “That is very good coming prepared to be caned. I might take one stroke off for that if you manage to keep silent too.”

Paul holds my answer sheet in one hand and the birch cane in the other. I hear the whoosh of the cane through the air, hear it smack onto my ass-cheeks. For a split second I feel nothing and then it is as if someone has laid a red-hot iron bar across my ass. Stinging radiates out from my ass in an explosion of pain. I grit my teeth together to avoid crying out. I don’t know if I can take it. Gradually the ache diffuses. I am trying to work out how many answers I might have got wrong when another whoosh foretells the next stroke, the next painful slash across my white cheeks, carefully positioned in a slightly different place from the first. I push myself harder into the seat of the chair. I can feel tears but I’m determined not to scream in pain or cry out for mercy. In among the pain and the tears, however, I notice that my body is really aroused. It feels like my juices are seeping from my pussy.

After four or five strokes, I’ve lost count, my tears are running copiously. I’m whimpering a little, just wanting the punishment to end. However, I can feel my pussy almost dripping with excitement. On one particularly painful stroke I can’t help myself and I cry out.

“A pity,” says Paul, “That was the eighth stroke. You got 3 questions wrong and I was going to let you off one stroke if you were silent. But now you have a ninth stroke to come.”

Paul stands there waiting, letting me endure the throbbing across my ass cheeks. He reaches out with the cane and with the end he jiggles the padlock in my pussy. It is as intense as a vibrator on my clit, sending out waves of arousal. I am surprised that I am close to coming. As Paul continues to wiggle the lock with his cane I can feel my orgasm build. But just before I come he stops, leaving me frustrated. Now I just want to get the caning over with, suffer the indignity of the last stroke. My tears have dried up now. With a whoosh and crack the last stroke, the hardest of all, assaults my defenseless ass. The pain is too much. I cry out again, my tears run free once more.

As I lie pressed against the seat I feel something cool on my cheeks. Paul is rubbing ointment or something to start to soothe the pain. I can feel his fingers on the ridges that the cane has raised on me. I can only imagine my ass, white cheeks criss-crossed with red wheals. Paul rubs ointment into the crack of my ass too, slipping lower so that he is gently circling a finger on my tight asshole. Nobody has ever touched me there before but already I want him to push into me, I want to feel his finger in me.

“You’re a virgin here aren’t you?” Paul says as his fingertip nestles in the center of my asshole. I can feel myself starting to open up to him. I wish he’d just push it in, I want to know what it feels like.

“Yes,” I admit.

“But you want to try it don’t you?” How does he know that?

“Very much,” I say. I’m hoping he’s going to fuck me in the ass right now.

But it is not to be, at least today. He tells me to stand up. My skirt falls back into place. He hands me a tissue to wipe the tears off my face. Before I’ve really recovered my composure, he tells me when my next lesson will be and shows me to the door.

**

You want to know about my next lesson, don’t you? It starts off much as before. I arrive at Paul’s house, we talk casually without a word being said about sex. Then we spend about an hour going over the next section of the book. Finally, it is time for my test. Paul picks up the sheet with 10 questions on it like before.

“Strip to your waist,” he orders. Finally he is interested in seeing my breasts.

I unbutton my shirt and take off my bra. He seems to like what he sees, not surprisingly. He reaches out and strokes them, sending electric twinges through my body. He massages the areola around my left nipple. I can feel the blood rush into my nipple, feel it harden. He takes the nipple between finger and thumb and tweaks it harder. The nipple is as hard as a pebble. He reaches into his pocket and brings out a small metal clamp. What on earth is that? I’ve never seen something like that before. He reaches out and puts it on my rock-hard nipple. It has a small knob on it that tightens a screw thread. He tightens it up, enough to hold it in place on my nipple but not enough to be painful. He then wakes up my other nipple until it, too, is rock hard and puts a second clamp on it. Somehow I have the impression that my nipples are not going to enjoy the test.

“Have you ever had clamps on your nipples before?” Paul asks.

“Never.”

“They can be very painful,” said Paul casually. I have the feeling that he is right.

I look at the sheet of paper. The first question is easy and I write down the answer.

“Very good,” Paul says.

The second question is easy too and I write down my answer.

“You’ve made a careless error, you’ve put a plus sign when you meant minus.”

I look down at the paper. Of course Paul is right, I knew the answer but I just wrote it down wrong. Paul reaches out and holds the two knurled knobs, one in each hand. Without saying anything he tightens them. An intense spasm of pain spirals out from my nipples blocking out any other thoughts. After a few seconds it subsides a little and I can control it. I’m breathing hard, using concentration to block the pain. I look down at the third question. I get all the next few questions correct, thank goodness, but then like last time the questions get harder and inevitably I get one wrong.

Paul holds the nipple clamps again. He pauses letting me anticipate what will happen. I grit my teeth ready for the pain that I know is coming. He twists the knobs tightening the screws so that small teeth on the clamp bite into my nipples harder. Again a bolt of overwhelming pain spreads from my nipples. My breasts feel like they are on fire. After a few seconds the pain subsides a bit but it is still much more intense than before. It is really hard to concentrate on the math questions with my nipples shrieking for total attention.

Not surprisingly I get the next question wrong too. The pain when Paul tightens the clamps is almost unbearable at first. I am crying now, my tears running down my cheeks. I can’t think of anything else other than the pain in my nipples.

“Masturbation will ease the pain a bit,” Paul says quietly.

I stand up and slip off my jeans and my thong. Paul watches me as I reach down and slip a finger into my crack. It’s the first time I’ve touched myself since I shaved. It makes my lips feel really soft. I’m very wet. I start to gently stroke my clit. He’s right, the pain does subside a bit, or at least the feelings of excitement from my clit distract me.

If you think about it, trying to do calculus while masturbating and with clamps biting hard into my nipples makes concentrating really difficult. I amaze myself by getting the next question right. Only two more to go. My run of good luck is short-lived, though, and the ninth question is wrong. Before I have time to even prepare myself, Paul tightens the clamps again, causing agonizing throbbing pain as the metal teeth bit harder onto my nipples. I masturbate myself harder to counterbalance the intensity of the feelings from my assaulted nipples.

Of course I get the tenth question wrong too. Paul tells me that he can’t tighten the clamps any more without cutting me. He pulls out two weights from his pocket and hooks one on each clamp. They don’t look all that big but they feel like they weigh a pound the way that they pull on my nipples. I grit my teeth to cope with the new level of pain, one finger rolling in fast circles on my clit as I use my other hand to fuck myself with one finger. Tears are flowing down my cheeks and dripping onto my breasts. Finally I’m coming, my orgasm washing over me like a breaking wave, for a few seconds the pleasure blotting out the pain. Once my orgasm subsides the pain from my nipples seems almost bearable.

Paul reaches out and undoes the nipple clamps and takes them off. I expected the remaining pain to go away almost immediately but in fact the opposite happens. As the blood rushes back into my nipples the pain level rises unbearably and I cry out in surprise. Paul bends forward and covers one nipple with his mouth, gently massaging it with his tongue. Gradually the pain turns to pleasure. Paul transfers his mouth to my other nipple, tickling it with the point of his tongue, driving out the pain and gradually replacing it with a feeling of warmth. Even when he takes my nipple gently between his teeth it is a delight.

As he continues to kiss and lick my nipples, he reaches down between my legs and runs his finger over my hairless outer lips. They seem more sensitive than normal. His finger pushes between them, touching my inner lips but just avoiding my clit, teasing me. My clit feels like it is standing erect straining to reach his finger. I can feel juices leaking from my pussy and running down my ass-crack. His finger is touching my clit now, very lightly, making small circles and sending shivers of pleasure through me. Another finger touches my inner lips back near my entrance and then slides lower to my asshole. I’m really desperate for him to penetrate the tight ring, he knows I want to try it. But he continues to tease me. He’s not quite touching my clit hard enough to make me come, he’s not quite pushing his finger into me, just tantalizingly close.

Suddenly he starts to stroke my clit hard and fast, he bites on my nipple generating darts of pain, and he pushes his finger roughly into my ass. My latent orgasm explodes like the finale of a 4th of July fireworks display. I’m moaning loudly, the pleasure is so intense and seems to go on for ever. As my orgasm dies away I realize I’m breathing hard as if I’ve been for a 5 mile run.

“Next time it will be my cock in your ass,” Paul says. I can’t wait for my next lesson now.

**

I split up with my boyfriend earlier today. He came round and, of course, he wanted to have sex. I didn’t want to tell him about the padlock. I know, I was a coward. I know he could have fucked me in my ass, that’s not locked up. But I’ve asked him before but he always said it was weird. Of course it’s weird, that’s what makes the idea so exciting. Besides, now I want Paul to be the first person in my ass. Anyway, we had a big fight because I wouldn’t have sex and he stormed off.

So here I am, sitting at my desk. Can you believe that I’m voluntarily working on calculus? I may want to get punished but I don’t want to get punished too hard. My nipples still ache from last night’s treatment. There’s a knock on my door.

I open it and it’s Paul. That’s a surprise, I didn’t know he had any idea where I stay. He comes in. He says nothing but he turns me around so that I am facing my desk. He bends me forward. I should have told you already but I’m wearing a skirt. He pushes my skirt up around my waist. All I’m wearing is a thong with not much more than a piece of tape that runs up between my ass cheeks. The red stripes on my ass cheeks are less angry now and have turned into dark brown bruises. I don’t really notice them any more when I sit down, unlike the first day.

I can feel Paul’s fingers between my cheeks as they pull my thong to one side exposing me. He pushes a finger into my pussy. Surprisingly, since it’s only a few seconds since I opened the door, I’m already wet with arousal and anticipation. Is he going to spank me or fuck me? Or does he have something else in mind?

Paul rubs his finger wet with my juices on my asshole. I push back a little against him, desperate again for his finger in my ass. This time my wish is granted. His finger slowly opens up my tight hole and gradually his fingertip penetrates deeper and deeper until he is fucking my asshole with his finger. Paul unzips his trousers. I can feel his cock against my cheeks now. Of course he is hard as a rock.

I have to tell you that my fantasies were right and it does feel pretty good having some attention paid to my asshole. I feel a dribble of cool gel between my cheeks and soon he is using a second finger to work the lubricant into my ass, really opening me up wide. Now my ass is getting fucked with two fingers. My tight hole is not so tight right now.

Paul pulls his fingers out of me and I feel his cockhead nestling against my asshole. I reach back and grab one cheek in each hand and pull my ass as wide open as I can. You know I’ve been dying to have anal sex and finally I’m about to do it. Paul pushes forwards. The feeling is incredibly intense, painful even. But it’s like wiggling a loose tooth, even though it is painful you want more. I’m moaning with a mixture of ecstasy and agony as Paul gradually works his wide cock into my distended asshole. Once his cockhead is inside me he starts to fuck my ass. It’s a totally different feeling from being fucked normally. For a start it feels taboo, which makes it more exciting. He reaches underneath my body and takes my clit between finger and thumb and gently masturbates me as his cock starts to go deeper. Finally, on each thrust, I can feel his balls banging against my pussy lips and his belly pressed against the back of my fingers where they hold my cheeks spread. Wow, this is so like a porn movie getting fucked in the ass over my desk.

Suddenly I’m coming. I wasn’t expecting it at all, an orgasm just came out of nowhere. I can feel my ass rhythmically clamping on Paul’s cock as I come. It feels so strong I’m worried I’m hurting him. He is thrusting harder now. It sounds like he is close to coming. A few more thrusts and he is pumping hot jets deep inside my ass.

Paul pulls out of me, zips up his trousers and departs without saying a word. I reposition my thong and stand up. It can only be about 5 minutes since I let Paul in the door but that was the most intense 5 minutes of sex I can remember. My first ass-fuck. But I can tell you it definitely won’t be my last. When Paul said that next time he’d fuck my ass I assumed he meant during my next lesson. Who knew that he had a little extra-curricular treat in mind?

**

Tonight it is my last lesson before the final test. You know the drill by now. I come round and we work on some math. Since it’s the last lesson we are doing the last couple of chapters of the book. Like you couldn’t have guessed that.

Paul is waving the sheet of ten questions. I wonder what the punishment will be tonight for each wrong answer.

“Tonight’s punishment is that you will have an orgasm for each wrong answer.” Wow. Not really a punishment at all. My first instinct is to answer all the questions wrong, but I’m not sure I could cope with ten orgasms. I think I’d pass out. I don’t think I’ve ever had more than three orgasms at one time, masturbating with a vibrator, one of those ones that has a cock shaped part that goes inside me and a rabbit on top whose ears stimulate my clit. Normally I get 3 to 5 questions wrong which seems about right so I decide to answer the questions as well as I can and see how it goes.

I get the first few questions right but finally we get to the first question that I have wrong.

“Masturbate for me,” he orders.

I stand up. I’m still dressed, remember. I decide I’ll take things slowly. I pull my top off over my head, reach behind and unclip my bra and let it fall. I caress my breasts, avoiding my nipples at first. I feel like I’m in a strip club, although there is only an audience of one. But his eyes are following my every move. I pinch my nipples and make them hard. They aren’t really sore any more from their day of punishment. I undo the button on my shorts and slowly undo the zip. I let my shorts fall around my ankles and step out of them. I’ve got a white thong underneath. It’s one of those ones that looks pretty normal and un-thonglike from the front and has almost nothing at the rear. I run my finger over the swell of my sex encased in thin white material. I’m still surprised when I feel the padlock. I turn around and show him my ass. The ass that only he has fucked, although there is a thin strip of white cloth covering that entrance right now. I part my legs and bend forward in what would be a really obscene view if I was naked. I reach back and slip a finger under the hem of my thong and into my pussy. I bet that looks really sexy. I bring my legs together and slowly slip off my thong. Once it is over my hips I let it go and it falls to the floor. I turn back to face Paul and lean back against the desk. I can feel his eyes on my hairless crack as I move my feet apart again to show him my most intimate place. With one hand I reach down and spread my outer lips and with fingers of the other I start to stroke my pussy. I’ve masturbated in front of a guy before, but just lying in bed. Never in such an exhibitionist way. Being watched like this is a big turn-on. I know that if I touched my clit I could come at almost any time but I don’t want to yet. I slowly push a finger into my wet entrance. My pussy that has not had a cock in it for ages. I start to slowly finger-fuck myself. I bet Paul’s cock is rock hard right now. I move the hand holding myself open and pull my outer lips up and out so that my clit is completely exposed, sticking out enthusiastically. Then I take my finger wet with my juices and gently caress the tiny pink button. My climax is almost here. I slow down a little letting the pleasure build up slowly, holding myself just short of orgasm, enjoying the moment. I shut my eyes to focus on the feelings of pleasure as I start to touch myself harder to take me over the top and into the blissful valley of ecstasy. The excitement builds up higher and higher. How long can I prolong it? “I’m going to come,” I shout to Paul. Finally, like a sneeze, my body detonates. Wave after wave of joy pulses through my groin, all the way to my fingertips and toes and my scalp.

I sit back down at the desk. It takes a moment for my body to recover and look at the next question. Another one correct. But then the next one I didn’t even answer because I hadn’t a clue about it.

Paul turns the desk chair around so that it is facing him. Without being asked, or even really thinking, I spread my legs for him. He crouches down so that he is now between my thighs. Of course I slide forward in my chair. He takes the small brass padlock into his mouth and gently tugs on my lips. He pushes his tongue into my opening, tasting my recent orgasm. Finally he is licking around my clit, creating a marvelous feeling of intense pleasure. He reaches out and uses his fingers to spread my outer lips so that my clit is more exposed to his tongue. Can you imagine learning all subjects like this?

Paul pushes my legs back so that my knees are over the arms of the chair. I’m spread wide open in front of him. He licks lower, probing my pussy again. And then lower, he’s not going to lick my asshole is he? Yes, he is. Wow, who knew there were so many nerve endings there. The tip of his tongue is opening me up, pushing into my puckered rear entrance. A finger starts to caress my clit as he continues to lick my recently discovered pleasure spot. I never really came all the way down from my last orgasm when I masturbated just now, so I’m pretty excited already. Now finger and tongue are swapping places, the finger pushing gently into my ass and the tongue dancing rhythmically on my clit. I won’t be able to hold off much longer. He really knows exactly what my clit likes best. He is fucking my asshole with a finger and my clit with a tongue now. I feel like a total sexual being, nothing in the world exists except sex. He slips a finger into my pussy too, so I’m being fucked in both holes. The sensation is perfect, and I ride my climax to the peak. It feels like my pussy and my ass are trying to suck his fingers in deeper as I come. Two fabulous orgasms, a girl could get addicted to this.

The next question is wrong too. Paul reaches into his pocket and takes something. I wonder what it is.

“The key to your cunt,” he says as if reading my mind. My cunt. I tend to think of it as my pussy, I’ve never noticed that cunt can be such an intimate word. With anyone else it’s my pussy but when I’m with Paul it’s my cunt.

He reaches between my legs and undoes the padlock and gently removes it from the piercings in my lips. I feel naked without it. Well, I am naked, but you know what I mean. I’ve got so used to it being there that it seems odd now that it isn’t.

“Come on,” say Paul, taking my hand. I’ve never been in the rest of the house. He takes me back to his bedroom and lies me down on his bed. He undresses. I’ve not seen him naked before. I’ve never even seen his cock, my one experience of it was up my ass with my face pushed into the papers on my desk. I lie on my back and pull my knees up to my breasts, offering myself to him. What was it he said that first day? I’ll only fuck you when you are lying on your back desperate for my cock. I never thought that was very likely to happen, but here we are.

He moves between my legs. I feel his cock nestling between my lips in the entrance to my cunt. He slowly pushes forwards entering me gradually inch by inch. A long moan escapes me as his cock steadily goes deeper and deeper into my body. It feels like his cock is going to go on forever until finally I can feel his balls against my ass-cheeks. He pulls back out of me, leaving a feeling of emptiness. This time he enters me hard and fast in a single violent thrust producing not so much a moan as a scream of excitement and surprise. Now he’s fucking me hard and fast. He holds my breasts to stop them rocking so violently as his cock hammers my defenseless cunt.

I don’t usually come when I’m fucked on my back. As if he knew this Paul grabs me and rolls us over so that I’m on top. I sit up straddling him, his cock impaled deep in my cunt. I start to rock my hips backwards and forwards, enjoying the feeling of his cock sliding inside me, and rubbing my clit against his body. He reaches up and strokes my nipples as I close my eyes and drive my body towards its third orgasm of the evening. And that would be the fourth of the day since I masturbated this morning in bed; I didn’t tell you about that.

Paul is thrusting his hips up between my thighs in time with my rocking. I’m going to come soon. I don’t think it is going to be as intense as the earlier orgasms but I’m not sure I could take another one like that without needing a nap. There is still one answer we haven’t looked at and I’m pretty sure I got that one wrong. I speed up rocking my hips, grinding my clit on Paul’s body. I squeeze my cunt muscles around his cock which intensifies all the feelings.

“I’m coming,” I shout although I don’t expect he was in any doubt. I sit up on his cock and take in the feeling of my cunt trying to milk it. I raise and lower my hips, enjoying the feel of his cock sliding in and out of me as the last tremors of my orgasm fade away. He is looking at me, as if inspecting my body. It must look pretty sexy, I suppose, with my big breasts up above and his cock sliding in and out of my cunt, the view unobstructed by any hair.

Paul pulls out of me. It seems he is not ready to come yet. He grabs the answer sheet off the bedside table and, to nobody’s surprise, tells me that I got the last question wrong too.

“Lie on your front,” he orders me. He reaches into a drawer beside the bed and gets out some leather cuffs which he proceeds to wrap around my wrists and lock in place. Each cuff has a length of rope attached to it which he fixes to the headboard. A pair of similar cuffs attach to my ankles and I am soon spread-eagled on the bed in a taut X.

Paul gets something more out of the drawer. He shows it to me. It is a black plastic plug shaped like an ace-of-spades but with a broader base. I have a bad feeling that this is meant to go up my ass but I don’t think it’ll fit. It’s wider than his cock. Paul squirts some lubricant onto the black plug. I feel him part my ass cheeks and then feel the point of the plug push into me. He works it back and forth and I can feel myself starting to open up a bit. But it is borderline painful when he pushes it forward a little bit further each time. I find myself panting to control the intensity as my poor distended asshole is invaded. Finally, just when I think I can’t take it any more it locks into place. I feel like I am split open. He kneels between my legs and I feel his cock slide back into my cunt. It doesn’t feel as if there is room in my body for both his cock and the huge dildo but somehow I manage to take them both. Imagine a threesome with one cock in my cunt and one in my ass. That would be really exciting.

Paul pulls out of my cunt and I feel the plug being pulled from my ass. I know what is going to happen next. I can feel him move over my back. The plug has made me so open that his cock slips straight into my ass without any resistance. My asshole still feels tight on his cock as he starts to fuck me. He reaches over and grabs something from beside the bed. I can’t see what it is. Only when I hear the buzzing do I realize it is a vibrator. He reaches underneath me and positions it so that it rests in the cleft of my sex. I push my body down against it as he continues to fuck my rear hole.

With a vibrator pressed against my clit and a cock up my ass I’m soon coming of course. But I don’t want things to end so I try and disguise it. It’s sort of the opposite of faking an orgasm. I doubt I fooled him, an orgasm is pretty obvious when you have your cock in the climaxing girl’s ass. But he doesn’t stop. He is fucking me harder and faster now. I think he must be getting close to coming. I press my cunt harder against the vibrator underneath me, I want to come with him.

He pulls out of me and I feel one of the wristbands being undone. I partially turn over and his cock is just at my mouth. I open my mouth and he gently fucks it as my tongue swirls around his cockhead. I never thought I’d suck a cock that came straight from my ass but, hey, he stuck his tongue in my asshole so it’s only fair. He must have been on the point of coming in my ass since it only takes a moment before I can taste the salty-sweetness as jets of come spurt into my mouth. And a moment later the vibrator’s tirelessness brings me to another climax as I press it hard between my lips fucking it into the mattress.

Paul unties me and we get under the covers and fall asleep in each other’s arms. To our surprise it is not until it starts to get light that we awake. It is the day of the final exam. But I’m confident that I’ll get my A grade. Confident, moreover, that I’ll get an A because I know the material and not because I fucked the professor.

I pick up the small brass padlock off the table beside the bed. I squat on the bed as if I’m going to pee, while Paul watches me. With difficulty, because I can’t see what I’m doing, I manage to thread the hasp of the padlock through the two piercings in my inner lips. I click the padlock closed. Once again it dangles between my legs.

“Only you have the cunt-key,” I say. “And besides, I’m signed up for integral calculus next semester and I may need some extra tuition.”