(Freaky biology, high speed pregnancy, casual snuff, maybe consensual, maybe too dumb to notice, implied gynophagia)

He watched as the two dozen giggling girls filed in and took their seats. There was very little difference in the herd, all five foot five, tottering around five foot eleven in their uniform six inch tall red heels. The short shirts of their uniforms were cut high in front to leave firm, high-nippled breasts bouncing merrily, tiny red plaid skirts left round bouncy asses bare and hairless cunts in front on full display as they dripped and dribbled over the wire leading to the battery box tucked in the top of their white stocking.

Twenty four nearly identical faces looked up to him expectantly. Big green eyes, narrow mouths with thick lips, shiny red lips and flashy blue eyeshadow, long blonde hair tied in high twintails with big red bows.

All identical, interchangeable, practically disposable.

He tapped the redhead lightly on top of her head, and she made a horribly lewd noise as she pulled eighteen inches of cock from her throat. She smiled cutely, then crawled to the pillow under his desk.

"Alright, class, settle down. Now, today, I have to teach you an important lesson. Ahhh... Katie, please, step up here."

Everyone turned and looked as a girl in the second row slipped from her seat and flounced up to the front of the class. She giggled, tipped her head side to side to toss her twintails, and slowly blinked her big green eyes. She seemed vacant and was struggling to put thoughts together, but she really was trying so hard to think.

"Katie, sweetie, how old are you?" He asked.
"I'm fifty three, sir!" She giggled. "Almost two months!"

"Very good, very good, Katie! You're a smart girl. Now please, bend over my desk and spread your legs wide."

A collective gasp and murmur of excitement ran through the class as Katie squeaked and squealed and pranced in a circle, before she draped herself across his desk and scooted her legs as far apart as she could, wiggling her rounded rump high in the air.

He gently stroked his fingers over the taut curve of her ass, spread her cheeks slightly. Her anus gaped slightly, slick with girlspit and lube.

Then, his fingers trailed over her taut, untouched vagina. The whole class gasped with Katie as her snug little labia unfurled.

"Class, do you know why you all wear this part of your uniform...?" He asked, lifting the battery box from Katie's stocking and pulling the cable taut. He fiddled with the dials a bit, making Katie's shrieks and squeals drown out the suddenly much louder buzzing from Katie's crotch.

The class was still, staring in rapt fascination as Katie's pussy dripped and flexed and did tricks. Slowly, a slim hand raised. At a nod from him, Stacy stood up and tried to keep her eyes on his, but she kept glancing back to Katie's cunt.

"S-sir, we- We wear the pacifier to, to keep our hole... Occupied, so- So we only ever... Um, we only ever use our mouths and our assholes."

"Good girl, Stacy! Come up and bend over next to Katie, please." He smiled as Stacy excitedly flounced up and snuggled next to her classmate, pressed hip to hip as they waggled their asses high, and heard the wet slurps and happy moans as the two girls started kissing.

He plucked up Stacy's control box and wire, and watched the class as he slowly but firmly pulled. They stared in fascinated shock as the working ends of the pacifiers made Stacy and Katie's underused cunts stretch and splay wide, the two girls shrieking in fear, but the intense sensations keept them pinned to the desk.

With a wet schlorp, the thrumming things popped free. A full foot long, vibrating forcefully, its surface was covered in short, broad rubbery spikes that meandered randomly around and across the thrumming dildo.

"Today, class, you'll learn why you all need to keep this hole plugged, unless you're absolutely certain it's necessary." He stepped behind Katie, grabbed the handles on her sturdy belt that held up her skimpy excuse of a skirt, and drove all eighteen inches of his cock deep into her cunt.

She shrieked and squealed and screamed as he rutted, but it wasn't a fight. It was just... Something she had never felt before. As much as the entire school loved the teacher's meat in their ass and down their throat, getting fucked in the cunt just... It felt right.

He did his best, but that tight virgin snatch worked magic on his cock, and it was barely sixty seconds before he grunted and held himself deep, unloading copious amounts of cum in Katie's cunt. After a couple seconds of rest, he ripped himself free and immediately thrust deep into Stacy's cunt, hammering deep into her tight little snatch while Katie slowly writhed in a mindless daze on the desk.

With a loud howl from himself and Stacy, he filled her cunt with a second boiling load of cum, then slumped over her, panting and gasping for a moment. Then he dragged himself free, cock dripping as he turned back to the class. "Betty, be a sweetie and help me, here."

Betty was a good girl, and was on her knees at his feet in a flash, gurgling faintly as her puckerfish lips worked around the base of his cock. He had barely noticed how fast she had sucked it all down her throat.

"Now, you've all seen and tasted semen in your time here, and I know you all enjoy it in your ass and in your mouth. But what you haven't been told is that it has a very special biological-"

There was a loud gurgling noise from the girls on the desk. "M-Mister, I, I feel- n-n-naaAAAAH!"

He smiled and nodded. "Originally, this process took a full nine months, but at some point in the last fifty years-"

Katie and Stacy shrieked and screamed in terror as they were suddenly hoisted up off the desk, their abdomens balloning huge underneath them, wailing as their cunts stretched open wide. Bloody red domes started to push out from inside their bodies, pulsing and throbbing, wrinkled ugly faces turning to the class as the tiny heads and frail bodies pushed from their mother's stretched cunts. Tiny arms reached out instinctively, their bodies stretching and inflating, young children hanging by the waist from their mother's cunts, adolescent hands reaching the floor.

Katie and Stacy were sobbing in pain and fear and relief as the grown women lie panting on the floor behind them, long purpling umbilical cords reaching from the new women's navels, up between their ankles into their mother's stretched cunts, their feet still inside.

"... Sometime in the past fifty years, something happened to make the process much faster."

The class watched in shocked fascination as Katie and Stacy grunted, cunts disgorging wads of bloody afterbirth with the new girls' feet, the two on the floor shakily pushing up to hands and knees, then sitting up.

The collective gasp was followed by a long silence as the color came into their faces, natural pigment turning their plump lips blood-red and their eyelids shiny blue. But their skin was dark brown instead of pale pink, and their long hair curly and black instead of long, straight blonde.

Betty broke the silence with a loud slurp, pulling his cock from her throat. "They look like you, Teacher."

"Very good, Betty! They do look like me! And if any other teacher uses this special hole on you, the girl that climbs out of you will look kind of like that teacher. Say hello to Natasha and Isobelle, class, they'll be joining you from now on." He strode over to the desk, lifting the legs of the limp, shaking girls on the desk, and pulled their shoes from their feet. "Here, put these on, please. Hmmm... Amanda, Victoria, help Natasha and Isobelle get their pacifiers fitted. You can get the rest of the uniform after classes, but these are the important parts." He tossed the still-buzzing, still-dripping sex toys he'd pulled from the girls on the table to two girls in the front row.

"But, Teacher... What about Stacy and Katie?" Betty asked, tipping her head side to side like a confused dog.

"...Who?" He blinked, then looked back at the two stretched, sobbing, ruined cunts on the desk. "... Oh, them. Well. Normally, they'd have to rest for about a week or two to get back to normal. But, of course, you all know that there can only be twenty four girls in a class."

He grabbed the twintails of one of the girls on his desk to lift her head, and took the machete from the shelf on the blackboard. The familiar swish and thunk seemed to calm the class, who all giggled at the wet splatter of blood across the floor. With a second thwack, the issue of the two... Whoevers was quickly solved.

"Alright, ladies, I hope you remember what you learned here today. I know you have home ec next class, so please take the meat with you." He gestured dismissively at the headless bodies on his desk.

They had names at one point, but nobody could remember them.