<< Could be some unusual sexual fetish. There are quite a number of video clips floating around on edonkey and gnutella that deal with bodily wastes as a fetish (which I really just don't "get" for the life of me), but this may be a fetish of a more exhibitionist bent.
Then again, maybe the guy just had to urinate, and wasn't taking your presence into account? Nahh.. >>
Are you sure he wasn't drunk? I was coming home from a new year's party and saw some college kids pissing onto a tree in a dead visible position... Poor tree...
Edit: Jfur, you should have prentend staring at his thing, then when he notice tell him in sarcastic tone "I'm sooo sorry, I couldn't help, but look. I've never seen one that small "