Ty was fascinated by impregnation. One thing that he found really weird was just how many sperm one man could produce to one egg for a woman. He had so many inside him that would just go to waste, and he loved the idea of having offspring. And so a fun idea had come to him (pun unintended) while writing his list of possibilities- what if all the sperm inside him fertilized an egg?
Smiling, Ty made the wish, pulled off his clothes and began to jerk off right there in his room. The arousal he got from fulfilling his weird fantasy meant he didn't take long to cum, and when he did, the seed he pumped out onto his hand seemed not to stop, and every drop just raced away from him. All across the world, Ty's sperm swam into fertile womens' wombs. Not all of them managed to fulfil their goal, but even so, millions of them reached a waiting egg and wore away at its walls until they fertilized it. An absurd amount of women were now pregnant with Ty's seed.
Despite how absurd and unethical what Ty had just done was, he felt weirdly satisfied by it. But as it turned out, the wish would punish him for making it, as a strange sensation spread through his body. His completely spent testicles pulled up inside him and reshaped, turning into ovaries. His penis tugged up inside him until it formed a tiny sensitive clitoris, and his scrotum receded to form a vaginal slit. His chest swelled as breasts developed around it, and his figure altered as his shoulders narrowed and his hips widened. Ty gasped as SHE realized how she'd transformed- oh fuck, she was a girl too now!
And now she was, the very last of his sperm set about making her join the ranks of the newly pregnant women. A strong, energetic seed swam up her new passages, found her egg and weaned inside it, fertilizing it and guiding it to impregnate her.