We’d roll a bunch of the plastic caps that came in little rings in paper and light them on fire so the whole thing would blow up. I also remember one time at my school, there was this one kid, I think he was severely autistic, and one kid shot at him with a cap gun. This kid freaked out, kicked a massive hole in the wall (like a several foot tall hole), then took off running down the hall, through the doors, and down the street. The principal had to chase him down in her car. Dude was just Forrest Gumping it down the road.
Yo-yos were a thing at my school for a while too, but they eventually got banned because kids started hitting each other with them. Apparently, kids are basically cavemen and anything you give them, they will eventually figure out ways to hurt each other with.