I want to be pissed on.
It's not that I have anything specific for piss, not that I've admitted to myself yet. What I have is the knowledge that piss is still disgusting. Fucking? I love fucking, but it's a pretty normal thing for an adult to do. Hitting? Not normal, but... not disgusting. It can be glamorized, clad in slick black leather, ascribed a culture and even a sort of spirituality. It can be rationalized. It's probably not even uncommon. In my head and my social circle, hitting is okay.
Piss is not. Oh, I know there are people out there who are cool with piss, who see it as just another kind of play. Fortunately I'm not one of them, or I'd have to be shit on or something. (I do not want to be shit on.) I think pissing on someone in bed is fucking disgusting. It's not "naughty"--it's sick.
So you see.