Not the first time, but first time that was longer than a flash was in college. (My dorms had separate stalls with curtains. You would occasionally see or be seen getting in, getting out, or drying off. All fleeting moments.) During my sophomore year I went with a buddy to visit his friends at another school a couple hours away. We stayed for the weekend, sleping on the friend's floor. In the morning I headed to take a shower and was a little surprised to find it was an open area at one end of the bathroom, only slightly wider than a typical shower stall, with 2 shower heads. A guy who I had met the night before was in there using one. Now, I played sports in high school and shared a room with an older brother when I was younger, and I didn't mind being seen naked, but this setup would mean extended exposure in a pretty tight space. I was a little bit nervous about possibly becoming aroused. (As it happens, I had been discreetly checking out showering guy's ass the night before. Very hot body on this guy.) I hesitated for a brief moment, wondering if maybe it was customary there to wait for someone to finish, but decided that was silly. Dude saw me and motioned to the other shower head and said "I saved a spot for ya." He made conversation with me, offered me shampoo & squeezed it into my hand, and made me feel right at home—and also a little turned on by the attention. It really felt like he was flirting with me. I felt things stirring down below but kept moving while soaping up, etc. I definitely had some visible enlargement but it stayed below horizontal. I caught him looking at my plumped up cock once or twice. It was mostly just typical male bonding but the homoerotic undertones were there.