I was just thinking the US must have a very liberal attitude to nudity until I read the "Try taking a leak" paragraph. A man shedding all this clothes in a gymnasium about to be full of children should certainly be taken seriously!
On the one hand there are people who want the freedom to go naked, and I kind of support that idea, though I wouldn't want to do it myself! Especially in the chilly climate where I live! There is a man in the UK known as "The Naked Rambler" who used to wander the hills wearing nothing but socks and hiking boots. He managed to get himself arrested many times. But he seems to be harmless.
Removing all your clothes in a public place is quite different. I saw a guy doing this once when I was walking home. I called the police when I got home (this was in the days before cellphones) and they took it very seriously, and even offered me counselling (which I didn't need!).