If your hookup surprises you by suggesting some piss play, but you're not sure about watersports, there are many ways to handle the situation without ruining the date:

1. You can honor your date's fetish by proposing taking a piss into a toilet alongside him.  Say something like, "Whenever I first meet a man, I like to watch him take a piss as we urinate together.  Will you let me hold your dick while you do it?"  Once bladders are emptied, thoughts will naturally move on to other sexual possibilities.  But at least your date will have had some sexy piss play, even if it technically doesn't make you horny along the way.  If you're feeling a bit more open-minded, offer to let him watch you piss all over yourself in the shower.

2. If your date is a piss bottom, but you aren't ready to piss into a guy's mouth, offer to piss into a drinking glass for him to guzzle after the fact.  He'll get what he wanted, and you won't have violated your own boundaries.

3. If your date is a piss top but you definitely aren't ready to open your mouth as his urinal, suggest that he piss all over your body in the shower.  He'll get to experience the joy of dousing you, and you'll be soapy and clean moments later, no harm done.  Remember that unlike in the rest of the animal kingdom, if a man pisses on you, you don't become his "territory."