Cat girl

You don't need much. You already have the black cat-suit you plan on wearing in order to go to Victor's party as a 'cat-girl'. However you need a pair of black ears and a tail to really pull it off. Thankfully Madame Vivante seems to have what you are looking for, even if she seems to be without the usual bow-tie that comes with these costumes. You go in to the change room see how the ears and tail look and if the headband is too tight (you don't want to have to wear it all night if it is). You slip on the headband (which fits fine) and then decide to see how the tail looks. The moment you slip it on, however, you feel a sudden pain and realise that your jeans and, to a lesser extent, your underwear is digging into the base of your tail. You scream in pain and shred both the back of your jeans and underpants with your claws. It is only after you have done so that you realize that a) you should not have a real tail growing from the end of your spine and b) you should not have claws. With a growing sense of horror you reach up and find that you are not wearing a headband and that your real ears are now pointed and cat-like.

You step out of the change-room to ask Madame Vivante what the hell is going on only to find yourself on the rooftop of a city building. You suddenly realize four things. One, the costume shop has disappeared. Two, you are now entirely naked. Three, you can change, at will, from almost entirely human (pointed ears, cat's eyes, and black furred tail your only non-human traits) to black house cat and any point in-between. Four, you are so in heat that if you don't get fucked soon your going to loose your mind. You think about masturbating but you know that won't work. You know only a big hard cock or, at the very least, a long wet tongue will satisfy you and realise one more thing. You've just gone a little bi.