In college, I had pulled an all nighter working on a design project. Went back to the dorm to get a shower before my morning classes. It was still pretty early, and there was only one other guy in the gang shower. I took off my robe and started soaping up. The guy in the shower with me was hot as fuck, but I had never had a problem with controlling myself before. Maybe it was the lack of sleep, but very quickly I was at full mast, and it was not going to go down any time soom. I tried to keep my back to the other guy, but he had to have seen it if he looked at all.
Fortunately, nothing was said. I would see him again from time to time in the shower and never had another erection.