The Better Than Sex Pills you'd bought were the Venus brand, which implied exactly what you'd expect. And almost immediately, it started to feel so, so intense and good. Your chest rubs against your T-shirt and you pull it up, looking down to see your nipples have swelled and feel many times more sensitive. You reach down and pinch them, and an unusually high moan escapes your lips as you feel how large and warm they are and how smooth your skin has become. As much of the rest of your body shrinks and slims down, soft mounds start to expand on your chest and practically ache to be cupped and touched. Even if it hasn't finished, by now it's impossible not to recognize what's happening because of these pills: you're becoming female.
Your proportions are changing as your shoulders and hips inverse, the former narrowing and the latter widening, and you're forced to remove your jeans and underwear, standing there naked as you see a cute, thick butt form behind you. Under your new bust, you watch as the most masculine part of your body, your still-hard penis, becomes the last part of you to change sex. You groan in increasingly higher-pitched tones as you cum, your cock throbbing and shooting the last of your semen at first in spurts but soon in a messy trickle as it shrinks and slowly loses its functionality. Your milked testicles tug back inside you and you feel them adjust to become your ovaries, as the mound where they had sat sucks inwards and forms a slit leading inside your body, while the rest of your penis recedes into a clitoral nub.
Once you can focus on your feminized body, you're amazed by how total your emasculation and new embrace of womanhood is. When you see your old body's cum on the floor, you don't recall fapping so so much as the instinctive knowledge that if this semen were inside you you'd be knocked up, and a faint desire to be creampied. Even your kinks seem to have reversed. You pinch your nipples and imagine handsome men sucking on them. You carefully probe your slit and rub at your clit, biting your lip to avoid moaning out loud at the feelings.
Your intensely horny brain wonders what to do with your newly transformed body...