I went to a Prep school, and lived in the Dorm. All marble bathroom. There was a little stall in which the janitor kept his supplies, including a large bucket of the red or green treated sawdust sweeping compound. Cherry Bomb, with a Lucky Strike on the fuse as a delayed timer, into the bucket. By the time it went off, I was back in my room, playing banjo loudly. What an incredible BOOM! And the air full of smoking red sawdust? I was a suspect, but they couldn’t prove it! 8^)
“playing banjo loudly” was a great touch.
Buh duh bing bing, bing bing, bing bing bing...