"Jennifer, I hate you so much, I want you to die, but I can't bring myself to kill you, so instead, I'm going to destroy you. For your dare, no matter what happens, I dare you to remain in your house, and not attempt to contact anyone else or try to get help."
Jennifer froze. What was this creep up to? She wanted to hang up, but she couldn't!
"As for your transform, the instant I hang up the phone, you will begin to regress in age, a year every five minutes. This will continue before birth, but you won't die. Finally, you will separate into a sperm and an egg. Both of these will be mystically transported elsewhere; your sperm will impregnate a girl somewhere else in the country at random, while the egg will appear inside a different girl somewhere else in the country at random who is having sex, and it will be impregnated. For whatever reason, your new parents will carry the two halves of you to term and you won't be aborted."
Jennifer found herself able to talk. "Kyle, what the hell, why are you saying all that!"
"Shut up, I don't care anymore. I don't know what's going to happen to you, being split in half, but it's better than what I could do to you, goodbye!"
He hung up the phone. Jennifer felt her body shiver. She was already starting to grow younger...and there was nothing she could do about it.
She sat on her bed, looking into her full-length mirror, watching herself change. Her features began to soften, then her breasts shrank. Her bra and skirt became baggy. Twenty minutes later, she was little more than a freshman, with tiny little breasts and skinny hips. Ten minutes after that, her bra slid down her abdomen, as there were no longer any breasts to speak of. She took it off and tossed it aside. Another ten minutes, her sock slid off her foot. She shrugged out of her skirt and panties, they slid to the floor.
Another ten minutes...she was only seven now. She started to cry, but there was nothing she could do. Five minutes...a girl of six stared back at her. She couldn't watch anymore and lay back on the bed. Half an hour later, she was nothing but a newborn baby.
She couldn't think anymore, only feel. She kicked feebly, she was cold. She wanted to cry, but she couldn't.
She shrank into a tiny preemie, and beyond, into a foetus that shouldn't be able to live, but did anyways. Finally, a tiny microscopic blob of flesh...the cells coalescing back into a fertilized egg.
Some part of herself remained concious even to this point, and this tiny part of her, if it could speak, would have said "goodbye, Jennifer."
Then she was a tiny sperm and an egg....there was a flash of light, and both vanished.
They never found Jennifer. She had apparently vanished, all that was left was some clothing she had worn, but inexplicably removed. No signs of sex, but her blanket was soaked in some amniotic fluids, as if she had miscarried a child.
It was a bizarre case, but as the years went by, the town forgot about it.
Eight years pass.