BIGEST FAIL MOMENT: Overclocking an AMD Athlon Thunderbird.. Giant copper cooler with two Delta 80mm 9000rpm fans. Reached into the system to tweak some wires... and stuck my thumb into one of the Delta fans. Killed the CPU, and ripped a chunk out of my thumb.
I may have posted this earlier - but I located the fan (yes this is the actual fan that tore a chunk out of my thumb) and decided to post a picture of the scar on my thumb.