When I was 10 years old, I formatted the hard drive from my old computer and never bothered to back up my data beforehand. I lost some old photos and videos because of that. I also broke the computer by disassembling it and not knowing how to properly put it back together.
I also threw a Hot Wheels car at my TV because I missed an episode of Unwrapped, the only damage it caused was it left a tiny white speck on the top of the screen.