I was cutting a cardboard box up with a box cutter, holding the box steady with my off hand while pushing the blade downward through the cardboard. I realized that my hand was below the blade and therefore there was a risk I’d cut myself if the blade suddenly moved more quickly through the cardboard than anticipated. Safety first! So I stopped cutting, leaving the blade in the cardboard, and lifted my hand to grip the cardboard above where I was cutting instead.

Slammed my thumb right into the blade as I moved my hand, peeling a nasty slice of skin off. Took a lot of stitches to tack it back in place, still have a scar from that.