You're lying on your sofa in the living room, wiling the evening away by watching some romantic drama that happens to be on. It's not super interesting, but the actress playing the love interest is hot, so you figure when there's inevitably a sex scene, it'll be pretty fun to watch (plus you can't really be fucked to go look up porn right now).
But when the scene comes, something weird happens. Your eyes are drawn to the guy. His firm, toned chest and stomach, his thick arms, his impressive ass- for some reason, all of it is more interesting to you than his co-star's body. Not only that, but your thoughts and arousal seem to be different too. You still think of yourself as straight- always have, always will- but this feels straight. It's like you're disconnected from thinking of yourself as a man.
Seeing him kiss down her neck, you wish the guy was doing that to you. Your hand traces the nape of your neck, and you faintly notice your stubble has vanished. You pull off your T-shirt and run your hands down your torso, barely noticing more than faint shivers as your figure turns slightly more curved.
Soon after, you feel intense twinges in your chest as your nipples perk up and grow. You can't help but imagine having them rubbed, pulled, pinched, sucked, bitten. Seeing breasts bud on your chest, you find yourself feeling them up and enjoying the sensation of growth around them while your body shrinks and gets more shapely elsewhere.
Speaking of elsewhere, between your legs you're beginning to feel strange. You pull off your pants and boxers, and see that your shaft is erect and sensitive without having gotten long and hard. You reach down and rub your head where it pokes out from your foreskin, and a high-pitched moan escapes your lips. It dawns on you- you don't have a penis anymore, you have a clitoris. You're turning into a woman.
As you realize this, you feel your balls move up inside you, and a passage starts to form between your legs. The implications of your new body are dawning on you now- you aren't gonna be able to fuck people up anymore, you're going to get fucked. You can take a cock in your hot wet slit and... oh fuck. You can get bred now, and for some reason the thought is turning you on. You can't stop thinking of men pounding your new pussy, filling you up with their cocks, as you watch your former cock shrink and shrink, growing more and more sensitive in the process.
At last you feel your slit open, and your new vagina rapidly moistens from your arousal. Looking down at yourself you confirm it in your mind- you've turned into a woman.