Like others have commented, not into watersports here, but htere was just something so primal about watching a buddy take a piss. Being new to guy fun I was intrigued by how open minded I could be with a guy as we explored guy fun. I asked a buddy once to hold his dick while he took a piss just to see what it was like - it felt so fucking cool just to do that with a guy. He held mine after while I pissed. We both really liked it.
Ended up asking another buddy to do it, and he didn't want to right away, but later told me if I wanted to try it he was cool with it. His was much smaller than my other buddy, and I realized I was having to push it down into his balls to aim it at the toilet. It was an eye opening experience for me. He never ended up holding mine, but he said if he had he'd just end up being jealous of my length and pissed off, so he decided to avoid the whole being mad thing. That was good for my ego.
Again, just seems like such a guy thing to do by holding each other's dick while pissing. Just gives you a whole new perspective of what other guy's feel when they hold their own dick to piss.