You've got AIDS.
But you're really fit. You're practically a magnet for the opposite sex (or the same sex, if you're homo)'s genitals. You don't like long term relationships, and every fortnight or so, you sleep with, and have sexy on a girl/boy.
Now, a mystic spirit is watching you, and makes sure, that you MUST, repeat, MUST take one of the following options, or he'll kill you.
Never have sex ever again, including mouths and bottoms AND hands.
Carry on sexing loads of people, and not telling anyone. Also, you're never allowed a condom ever again.