Only once. I was playing in a company golf tournament and came into the locker room after the round. As I turned the corner around some lockers there was this guy I worked with that was a complete asshole. He did nothing but make my life miserable. Anyway, as I walked up I caught a glimpse of what was clearly a very small limp cock. It just flashed through my head, "Oh, you can't pass this up" and I took the locker right next to him. He seemed uncomfortable right away and the body language was classic at the point that it was clear he'd seen my cock. We both went into the shower. He faced the wall the whole time and finished in about 30 seconds. He was gone when I got back to the locker. It was juvenille, but really funny at the time.