Hmmmm...
being a lifetime combo of nerd and martial arts fan there are SO many to choose from,
but for sheer unadulterated "Darwin Award" stupidity deciding to cut a piece of silk
(to make it worse it was for a headband)with my first ever "live blade"(I.E. fucking SHARP) Katana by kneeling on a bouncy bunk bed with the sword held blade up towards my stupid 12yr old face and sawing said silk vigourously up and down the razor sharp blade takes my top award...
Of course physics took over when the silk parted and the blade sprang up at my thick skull like a playful kitten-smashing me full in the face vertically from left side of forehead through cheek and lip...and chin...
Oh how my sister laughed when she came home(not) and found me looking like freddie krueger and edward scissorhands had decided to play knoughts and crosses on my face?...
Did I mention I was babysitting my first nephew at the time?
ah,the good ol' days....