I went swimming in my local pool one day a few years ago. The changing rooms are obviously male and female divided, but the male changing rooms are just a large area with lockers on the walls, and a bench in the middle. I don't mind being naked infront of others, in fact I'm a bit of a nudist.

I had worn my swimsuit to the pool as it was summer, so didn't need to change before going in. However after the swim I wanted to have a shower, so had to strip off by the lockers.

There was around 4 or 5 guys already in the shower, and as I made my way over, they stared at my penis. I'm about 5' inch flaccid, so nothing crazy, but at the time I was pretty thin which accentuated it.

I started showering, but a few guys kept staring, and it started to give me a boner. Eventually after trying to hide it, I was fully erect (I'm just shy of 7.5 inches) . I felt really embarrassed that I got hard, so I quickly darted out of the shower and used the wall locker door to hide it while I got dressed. I made my way out pushing my erection down into my shorts as I walked outside.