Holy crap, yes! I have 3 stories, although one isn't really a penis sighting.
Saw Bill Lambeer (sp, since I don't really know who he is, but my mom did) about 10 years ago. She was really excited when we saw him outside, and I followed him into the bathroom, but he took a stall.
But, about 8 years ago, I went to France with my class and saw Paul Walker in the bathrooms. He was only there for maybe 10 seconds, as I got there way after him. I didn't really know him then, like, at all, but when I saw Varsity Blues, I was like "HOLY SHIT!" I didn't really get to see anything. I saw a little bit, but since he was like 3 urinals away, not much. I'd guess around 5 soft. possibly uncut, hard to tell.
But the best one I have, the one I can remember vividly, was last year, I was flying up to Michigan to see my grandparents. I got stuck in a layover and had to wait about 8 hours because of the snow. Anyway, later that night, I went to use the bathroom, and I had my headphones on (I can still remember listening to "Hand in My Pocket," by Alanis). I was about to finish up, and Ricardo Medina Jr. comes waltzing in, and I couldn't understand what he said, since my phones were on, but he took a leak right next to me. Definitely packin some heat there. I dunno if he was semi-hard maybe, but at the time, I'd have to guess around 7 inches. Either way...he's sizzling hot. But he came off as a real douche on Kept.