Extra Credit: Human Anatomy

The head of his cock pushed into the back of her throat and he pulled back, slowly, until he saw her lips stretch around the swollen ridge, and then pushed back in, all the way, feeling her throat clench and swallow around him.

"Oh my god," he groaned, holding her face as he slid in and out. Her eyes began to water, and makeup ran in dark lines down her face.

"That's excellent work, Lydia," said Miss Kay, coming around to look. She slapped the girl's glistening cheek lightly where his cock pressed against it from inside, giving him a jolt. He popped out and the teacher reached down, making a ring around the base of his erection with her cool fingers.

"Alright girls, this is an important lesson," she said, holding him tight, so he pointed straight out and up. "We've put young Bill here into a state of extreme arousal, and we have a responsibility to follow through for him now. A man left like this could suffer serious health consequences. He needs to slide that cock into a tight pussy and fuck it hard and deep." She punctuated the last few words by slapping his wet erection against her palm. "So that is what we will demonstrate now. Do I have a volunteer?"

The girls glanced at each other for a moment, and a few hands went up. Amy was bouncing up and down and mouthing 'pick me' over and over.

"Amy, why don't you stand here. And go ahead and disrobe as well, dear. Let the class see clearly."

"Yes ma'am." She grinned at Bill as she undid her shirt and pulled it off, revealing full, round breasts topped with light pink nipples, hard and nubby. She turned around and glanced over her shoulder before bending over and pushing her skirt and panties down to her ankles. Her pussy was smooth with full, pink lips, and the inside edges of her slit glistened with moisture.

"That's good, dear. Hold that position for a moment. Here, you can hold onto my desk." Miss Kay guided the girl so that her legs were straight and parted, and she was bent over at the waist, reaching the full length of her arms to grab the edge of the desk. "Come take a closer look, class," she said, reaching out to lightly stroke Amy's pussy as the other girls gathered around to watch. She parted the girl's labia with her fingers, displaying the wet opening within. "As you can see, Amy's vagina is displaying signs of sexual arousal, enlarged labia and vaginal secretions." Amy shivered and let out a quiet moan as the Professor slid a finger inside her, and began to slowly move it in and out. "It's very important to ensure the female is properly aroused and lubricated before penetration by the male. Bill, come up here now."

He stepped forward and Miss Kay took hold of his wet, throbbing cock. She smiled at him and ran her hand up and down his length, curling her cool fingers around the head, then back down to fondle his balls. She pulled him toward Amy. "When a man is fucking a woman, she belongs to him," she said, and slapped his cock on Amy's ass cheek with a loud smack. "Her body is his to use as he likes," she continued, with a slap to the other cheek that left a little splatter of pre-cum slick on her skin. "Go ahead and enjoy her, Bill. She's yours."

"Yes, Miss Kay."

Bill reached out and laid his hand on her soft, pale ass, giving it a squeeze. He used both hands, squeezing her curvy cheeks, and leaned into her, spreading them apart with his palms, stretching the skin between and making her pussy lips pull open with a wet squelching sound. One thumb grazed her asshole and rested there, gently pressing and rubbing the tight ring of muscle. He felt it tighten at first contact, and then slowly relax and stretch, allowing the pad of his thumb to sink in slightly. Amy groaned and moved her hips, pushing back against the pressure.

Miss Kay guided Bill's seeping cock to the moist folds of Amy's pussy and rubbed the head up and down her slit. Her lips parted and his cock slipped between them, sliding down against her clit, then up toward her ass, back and forth. Amy was letting out little gasps and moans with each pass over her sensitive nub.

Bill leaned forward and the head of his cock pushed into her opening about an inch. Her labia stretched around him and she shivered and her moans turned into a soft "aaahhhhhh, aaaahhhhhh" as he pressed in. It was so tight he pulled back, watching himself emerge from her flesh, watching her lips close after him, like they were giving the tip of his cock a kiss. He leaned in again, sliding into her, a bit easier this time. The ridge of his cock head disappeared into her pussy and he pushed on, sinking farther in, feeling the muscles inside her clench and squeeze his thick erection. He pulled back once more, part way, and grabbed her hips, and thrust forward until his cock was completely buried, eliciting a loud yelp.

"That's right, Bill, show her what you need. Take her how you want her."

Bill smiled, looking down at Amy's pussy, skin stretched tightly around the base of his cock and glistening with her juices. He rubbed a circle on her right ass cheek with his palm, and then delivered a sharp smack. "Ooh, oow," she gasped, pussy pulsing along his length in response.

"Very nice," whispered Miss Kay in his ear, as he pulled back, watching his cock emerge from Amy's vagina. The Professor's mouth closed on his ear, warm and wet, sucking softly. Her hand was stroking his back, and down to his ass. He felt her nails as she slipped her fingers between his cheeks, brushing along his asshole, lightly scratching at the insides of his thights. "Do it again," she said, licking behind his earlobe.

Bill gave Amy another loud slap as he pushed back inside her, making her quiver and cry out with a mixture of discomfort and pleasure. Her knees were trembling now as he slowly fucked her, sliding his full length in and out of her tight canal. He leaned forward, letting his weight rest on her back, and moved his hands up her sides to find her breasts. They were swinging with the rhythm of his long, deliberate thrusts. He cupped them in his hands, squeezing the soft flesh. Her nipples were hard against his palms and he pinched them between his thumbs and fingers, gently at first, rolling them a little. Her moans were constant now, rising in pitch as he gradually increased the pressure.

"Ohhh fuuuuuck," she groaned.

He could feel the second orgasm building up in his balls, a tingling sensation rising up the length of his erection, getting close. He fucked her faster, letting her support his weight and just enjoying the feel of her tits in his hands and her pussy tight around his cock. He pulled on her nipples and she let out a series of loud cries he was sure could be heard down the hall, her whole body shaking as she came, her insides spasming around him. He felt the cum suddenly rush up through him, felt Miss Kay's fingers cradling his balls as they pumped the semen out in heavy spurts, felt it thick and clumpy gushing from his cock, filling Amy's pussy, some seeping out to dribble down her thighs. He clutched her body and ground his cock into her hard as he rode out the orgasm, and she pushed back, still trembling with the aftershocks of her own.

The cum was dripping down his balls now, and onto Miss Kay's fingers, which were still gently fondling him there. She didn't seem to mind, in fact she was smearing it all over his sack, rubbing it into his skin like lotion. The three of them stayed that way for a few moments, Bill and Amy catching their breath as his erection slowly subsided inside her. Finally Miss Kay removed her hand, wet with his semen, and raised it to her mouth, tasting a couple of fingers.

"Mmm," she said, watching as Bill's softening penis emerged from Amy, with a dribble of cum spilling out after.

The girls let out a little cheer at the conclusion of the demonstration, gathering around Amy as she stood up, giggling and offering words of approval. "That was awesome, Amy," said Rachel, grabbing the other girl's hands with excitement. "How did it feel?"

"Amazing," said Amy breathlessly. "I can't believe it!"

Some of the girls closed in on Bill, as well, slipping themselves in so his arms went around their shoulders. "Wow," said Cynthia, inches from his face as he leaned on her for support. "You were so hot fucking her," she said, running her hand down his stomach. She scooped some of the mingled cum and pussy juice from his cock and licked her fingers, smiling at him. "I just wanted a little more."

"Oh god," he said, watching her swallow.

"Okay girls," said Miss Kay, "that's about all for today's class. But before you leave I want each of you write your name and phone number on Bill here. He's going to have uncontrollable erections for weeks, maybe months, whenever he thinks about what happened here today with all of you, so I expect each of you to do your part to relieve him. So when he calls, you drop what you're doing, go where he wants you to go, and do what he wants you to do, understand?"

A chorus of voices said "Yes, ma'am." She passed out a few sharpies and the girls started taking turns writing on his chest, arms, stomach, as they filed out of the classroom.

"Can I, too, Miss Kay?" asked Amy, pausing as she pulled up her skirt.

"Of course, dear. I'd be very surprised if he's done with you just yet."

She grinned and hurried over to scrawl her number on Bill's palm. "I think I might need some more spankings," she whispered. He just stared after her as she shrugged into her shirt and left the room.

It was just him and Miss Kay, now. Bill stood awkwardly, naked, still dripping with cum, and she walked up to him, heels clicking on the hard floor. She slowly dropped to her knees and looked up at him. "I suppose I should do my part as well, don't you think?" she asked, taking his wet, semi-flacid cock in her hand. Even after two orgasms he felt it begin to thicken on her palm. She leaned down and licked the top side clean with one long stroke of her tongue, before uncapping a marker and writing a number across it.

"See you in class tomorrow," she said as she walked out.