In high school all the cool kids were doing this trick where you'd cup your hand on your desk palm down, fill up that cavity with gas from a bic lighter, and ignite. Usually it would just flare up for a second, then continue burning for another second or two so it looks like your hand is on fire. One day in algebra class I went full idiot and filled it up for like 5 minutes, so when I lit it it went WHOOSH!!!!! pretty loud and the fireball was as wide as my desk. The teacher had his back turned, spun around and said "What was that?!? Who did that?!?". Everyone around me was laughing and luckily nobody ratted me out. Teacher just shook his head and sighed.