The only nudity I ever saw in the gym that seemed weird was this one guy, done a lot of body building, standing naked in front of the full length mirror admiring himself, throwing a couple of poses, and a couple of wannabe bodybuilders standing with him, also staring at his reflection, and oohing and aahing.
I guess there was also the other guy at the same gym. He was about 50, Italian maybe, and I think he'd worked out too hard. He was disoriented. Once he got his clothes off, he kept trying to go out of the change room into the workout area. Eventually, there was a wrestling match between a couple of the workers, and this naked guy, to keep him there till an ambulance could be called.