I would love to post but even after 35 years I'm still not certain the statue of limitations have expired!
Got caught in 11th grade making nitroglycerin after school in the lab. But didn't get in any trouble at all. Teacher was impressed how far we had gotten and how controlled the experiment was. It also helped our case that we stole the formula out of this same teacher's desk. He wasn't stupid as that was the tip off to him what we were up too!
Also there was a helium tank in the supply room so one day we rigged a 3 way supply with shutoff valves on hoses out to our desks, neatly hidden I might add and we'd raise our hand for every question and we sounded like Alvin and the Chipmunks. The best part was the next day the teacher did a reverse and taught the better part of the class taking an occassional hit of helium. We had tons of fun but we learned a lot because it was fun.
Made an A in chemistry too and it was earned. Parents still regret that chemstry set for Christmas they got me. What didn't stink, we blew up!