This is going to be a compilation effort of idiotic things that people do in gyms.
I would venture to guess that for every clip that can be found on YouTube, there are probably 100 more that happen without being captured on video.
Check out 2:24min into this lovely compilation
Look, I have personally seen guys squatting in a pair of jeans, or even a guy who was running intervals in a full soccer kit (jersey and shorts) with CLEATS on the treadmill.
DON’T MAKE THE YOUTUBE HALL OF FAME DUMB GYM LIST.