The principal's office was dimly lit by the late afternoon sun filtering through half-closed blinds, casting a warm, intimate glow over the large mahogany desk and leather chairs. The air felt heavier now, thick with the scent of sweat, cheap cologne, and the faint musk of arousal. Principal Wang sat sprawled in his oversized leather chair, his fat belly rising and falling with heavy breaths. His bald head glistened under the light, small pig-like eyes filled with greedy lust as he kept Teacher Zheng firmly seated on his lap.
Teacher Zheng's massive D-cup breasts were completely bare, heavy and pale, glistening with the old man's saliva. Her swollen, red nipples stood out prominently after the long, greedy sucking session. The tight black pencil skirt was still bunched up around her slender waist, and her sheer black stockings clung to her thick thighs. She maintained her professional composure as best as she could, thin glasses slightly fogged, long black hair still mostly pinned up despite a few stray strands falling loose.
Principal Wang's fat hands never left her chest. He continued to squeeze and knead the heavy mounds, occasionally pinching the sensitive nipples between his stubby fingers while his small, hard erection pressed insistently against her plump ass through his pants.
"Very good lesson so far, Teacher Zheng," he said with a filthy grin, his voice low and hoarse. "You explained the breasts and nipples perfectly. But biology isn't just about tits and milk. A real man needs to know how to produce a baby. That's the most important part, isn't it? The reproductive system. How a woman's body gets pregnant."
He gave both of her massive breasts a rough squeeze, making them jiggle heavily in his hands. "Keep teaching, slutty professor. Explain step by step how to make a baby. Use your own body as the example. And don't stop even when I touch you."
Teacher Zheng took a slow breath, suppressing every real sensation, and began in her clear, educated biology-teacher voice, even as she sat half-naked on the old man's lap:
"The process of producing a baby begins with sexual reproduction. In humans, it requires the union of male sperm and female egg. The female reproductive system includes the ovaries, fallopian tubes, uterus, and vagina…"
Principal Wang chuckled dirtily, one hand sliding down from her breast to rest on her thick thigh, fingers tracing the edge of her stocking. "Keep going. Tell me about the pussy first. Describe your own cunt while you teach. How does it get ready for a baby?"
Teacher Zheng's voice remained steady, though a faint tremor entered it as the old man's hand moved higher. "The vagina is an elastic muscular canal… approximately 7 to 10 centimeters long in its resting state… but it can expand significantly during arousal and penetration. When a woman becomes sexually excited, the vaginal walls produce natural lubrication… to facilitate easier entry of the penis."
The bald old man grinned wider, his free hand returning to maul her left breast while the other rubbed slowly between her legs through the thin fabric of her panties and stockings. "That's it… talk dirty about your own pussy, Teacher Zheng. Is your cunt getting wet right now while you sit on my lap? Feel how hard my cock is pressing against your fat ass. That's what's going to put the sperm inside you."
He pinched her nipple hard again, rolling it between his fingers as he spoke.
Teacher Zheng let out a soft, suppressed moan. "Ah… during arousal… the labia swell… the clitoris becomes engorged with blood… and the vaginal canal secretes clear, slippery fluids… making it easier for the penis to enter and… deposit semen deep inside."
Principal Wang's eyes gleamed with lust. He yanked her closer on his lap so her huge ass pressed more firmly against his erection. "Good girl. Now tell me what happens next. How does the sperm reach the egg? And where exactly is that egg waiting in a woman like you?"
His fingers pressed harder against her pussy area through the stockings and thong, rubbing slow, filthy circles right over her slit.
Teacher Zheng continued explaining, her voice growing slightly breathier despite her efforts to suppress it:
"The male penis… when erect… enters the vagina during intercourse. It thrusts back and forth… stimulating the sensitive walls. At the moment of ejaculation… the man releases semen containing millions of sperm cells… deep into the vaginal canal. The sperm then swim through the cervix… into the uterus… and up the fallopian tubes… where a mature egg may be waiting after ovulation."
Principal Wang groaned loudly, his fat belly jiggling as he ground his hard little cock against her ass. "Fuck… listen to you talking so scientifically about getting fucked and filled with cum. So the sperm has to swim all the way up to your egg? That means I need to shoot my load as deep as possible inside this tight teacher cunt, right?"
He suddenly slipped his hand under the bunched skirt, pushing the thin thong aside. His thick, stubby fingers directly touched her bare pussy lips, rubbing them crudely while he kept squeezing her massive D-cup breast with the other hand.
"Keep teaching, Teacher Zheng. Tell me about the uterus and how it prepares for the baby. And moan properly while you do it. I want to hear how horny this lesson is making you."
Teacher Zheng bit her lip, suppressing the real feelings, but let a soft moan escape as his fingers teased her entrance. "The uterus… ah… is a hollow muscular organ… shaped like an inverted pear… It thickens its lining every month… in preparation for a possible pregnancy… If fertilization occurs… the embryo implants into the uterine wall… and begins to develop into a fetus…"
Principal Wang laughed filthily and pushed one fat finger inside her, pumping it slowly in and out while his thumb rubbed her clit. "That's right… my sperm is going to swim up and knock up this perfect womb. Imagine it, Teacher Zheng — your belly getting big and round with my baby while those huge tits fill with real milk. You'd be walking around the university with my child inside you, tits leaking, ass even fatter."
He added a second finger, stretching her pussy while continuing to pinch and pull her swollen nipple with his other hand.
Teacher Zheng's moans became more frequent, though still controlled. "Mmm… during pregnancy… the breasts enlarge further… due to hormonal changes… and milk production begins in the mammary glands… The nipples become more sensitive… and colostrum can be expressed…"
Principal Wang pulled his fingers out briefly, only to slap her pussy lightly a few times before pushing them back in deeper. "Keep going. Tell me exactly how I should fuck you to make sure the baby takes. Should I cum deep? Should I keep my cock inside after I shoot so none of my seed leaks out? Be detailed, you slutty biology teacher."
"The best chance for fertilization… ah… occurs when semen is deposited close to the cervix… during deep penetration… The woman can remain lying down afterward… to help the sperm travel upward… Strong contractions of the uterus during orgasm… can also help draw the sperm in…"
The old man's breathing grew ragged. He pinched both of her nipples hard at the same time, twisting them while his fingers fucked her pussy faster. "Fuck yes… I'm going to bend you over this desk one day and pump you full of my old man cum until it overflows. Your tight cunt is going to milk every drop. Tell me — once the sperm reaches the egg, what happens next? Describe how my baby starts growing inside your womb."
Teacher Zheng's voice trembled with suppressed moans as she answered:
"Upon fertilization… the sperm penetrates the egg… forming a zygote… It then travels down the fallopian tube… and implants in the uterine lining… where it begins rapid cell division… developing into an embryo… and eventually a fetus… The placenta forms… providing nutrients… and the mother's body undergoes many changes… including breast enlargement and… mmm… increased sensitivity…"
Principal Wang suddenly pulled her closer, burying his face between her massive breasts again. He sucked hard on one swollen nipple while his fingers continued pumping into her pussy. Wet, sloppy sucking sounds mixed with the lewd squelching of his fingers.
"Mmmph… that's it… teach me while I suck these fat milky tits," he groaned around her nipple. "Your body is perfect for making babies. These huge tits will feed my child. This fat ass will get even bigger when you're pregnant. And this cunt… this cunt is going to take my seed every single day until you're knocked up."
He switched to the other nipple, sucking greedily while pinching the first one. "Tell me more dirty details, Teacher Zheng. What positions are best for getting pregnant? How many times should I fuck you? And what if I want to keep cumming inside you even after you're already pregnant?"
Teacher Zheng continued the lesson between soft, reluctant moans, her heavy breasts bouncing slightly with each movement:
"Missionary position… allows deep penetration… and keeps the semen close to the cervix… Doggy style… also effective for… ah… deeper deposit… Frequency… several times around ovulation… increases chances… Even during pregnancy… continued sexual activity… is possible… and can be… mmm… pleasurable for both partners…"
Principal Wang finally pulled his mouth off her nipple with a loud pop, strings of saliva dripping down her glistening breast. His fingers were still buried deep in her pussy, curling against her inner walls.
"Perfect lesson, you filthy teacher," he panted, eyes wild with lust. "Tomorrow you're coming back here for more practical biology. I'm going to show you exactly how I produce a baby — by filling this cunt with load after load of my cum until your womb is overflowing. Now get dressed… but leave your panties with me. I want to smell your wet teacher pussy while I jerk off tonight thinking about knocking you up."
Teacher Zheng slowly stood up from his lap, her massive breasts still bare and marked with red pinch marks and saliva. She adjusted her skirt, picked up her blouse and bra, and handed over her damp black thong as ordered.
As she left the office, her steps were steady, but her mind was calm and devoted, already preparing the full report she would give later about every dirty word and touch.
The biology lesson on reproduction had been thorough — exactly the kind of filthy, degrading session that fed the dark hunger growing stronger every day.