When I was younger, and didn’t know better I would always get a Bonner in the locker room changing. At first I was really embarrassed but now I know it was normal for kids to react this way
I used to often get one in the changing room and in the pool I used to just carry on, coming from an open family and nudist it didn't overly bother me, quite a few of us would end up hard or semi hard in the changing rooms, even wanked in the showers a few times
First, there were no girls in my swim class. All swim classes were conducted on different days and different times. Boys were not allowed to watch the girls swim classes and girls were not allowed to watch the boys classes. That's because you had to swim in the nude or get an incomplete grade if you forgot your swim suit. The locker room and showers were "communal" . There were literally 30 naked boys running around the locker room and showering together. There were unexpected erections "popping up" all the time.
It's surprising how often boners pop up in all male changing rooms and showers particularly were they are communal
It happened to me only once in a change room at a leisure center. I have a rampant sph fetish ( small penis humiliation) I crossed paths with an ex girlfriends current boyfriend. He saw my tiny penis and I saw his much larger swinging dick. It was just in passing so I dont think he saw my cock starting to get hard. I covered up and changed under a towel before I got a full erection. When I got home I masturbated picturing him fucking my ex and imagining myself watching it while I played with my baby dick.
Every summer the high school pool was open for any kids that wanted to swim. I wasn’t much of a swimmer but the girls were there in their swim suits, so I was there too. Getting out of the pool was the problem due to the inevitable erection I had.
I was de-trunked at a pool in front of a group of girls from my high school. I have a tiny penis and it was shrivelled up to babysized proportions. The embarrassment was massive but so was the turn on. I didnt get an erection right away but after I fled the scene I masturbated in the toilets knowing they had seen my tiny dink.