[jwiz]

When I was young, I volunteered at a science museum who would, as part of their chemistry show, fill a balloon with hydrogen and ignite it off a tesla coil. One time, we (~15yo kids) convinced the person giving the show (maybe...college age kid?) to also mix O2 in the balloon, instead of only H2.

The boom was so loud that management folks on the other floors sent people down to see WTF was happening. I don't think he got into (much) trouble, but he sure never did that again.