Have you peed on a changing room floor? (swimming pool)

I used to just go in the pool.

There were some kids in my group who peed in the changing room. One of them was near a toilet, but she refused to go. All she had to do was flush it or go somewhere else, but she stood in one of the corners and randomly started to cry. Then, she was upset about how she "couldn't hold it anymore" and she crushed herself up and let it go. That was embarrassingly awkward!

I don't need to go again if I've already been in the pool.

Very common for boys to do so, not as common among men, yet many of us do, even in our sixties. It's just more convenient to let it go as you're changing clothes and it's not like it matters, the floors are wet anyway.

our boys do this all the time, more common for boys I assume.

It was a dare.

Yes. I was about 10 years old.