I never think about checking another guy out, and even if I did want to look, I'd be too concerned that I would get caught. 99% of the time I am not pissing next to anyone I'd like to see anyway.
When my best friend got married (a rough day for me), his reception was held in his parent's back yard, and they placed huge walk in trailers for bathrooms for guests. I went in the mens trailer and was pissing when my friend's younger brother followed me in. This guy was about three years younger than me, and we had always horsed around punching each other in the halls and generally giving each other a hard time. So he comes up to the trough and starts pissing, and starts up a conversation with me about how I had been done...all the while staring at my dick. When I finish, he keeps talking as I wash my hands, and is still pissing when I am done. I turned back around to look him in the eye, and he is still at the urinal flopping his dick around. He looked me in the eye, flopped it around...until I shut the conversation down and headed out.
Typical of me, I was sort of shocked by the whole thing, and following up on it as a hint wasn't much of an option. Later, I found out he did do things with guys when we were in school. In hindsight, I'm really glad I didnt do anything with him. It was his brother I was in love with, not him.
At any rate...I had totally forgotten about this whole thing until I was reading the urinal posts - and it all came back.
Come to think of it, there has been other stuff...but I will save that till later...