Well since my life has been pretty close to a huge chain of disasters, I'll just dig a few up.
1. heating up candlewax till it ignites and then pooring water over it. 10meter high flamebursts are nice, unless you're onder a roof that's 3 meters high.
2. Having learned from that experience next time we tried it out on the street, we just didn't know that due to the wind the flames wouldn't go straight up anymore, it was more a mushroom cloud at 1 meter hight. (luckily I wasn't the one lighting it that time, the guy who lit it lost a fair bit of hair)
3. Dropping a brick on my big toe while not wearing any shoes. It broke in 4 pieces, my toe not the brick.
4. Taking a jump while snowboarding not knowing what's behind it. Nearly jumped into a ravine.