Power tools dont have to be on to hurt.

I have this big old Bosch drill that I only use for one drill bit. Its a big auger, about 25mm dia for drilling through posts to hang gates.
I couldn't find the chuck key for this big drill so I stuck an old philips head screw driver in the hole and levered an old flat screwdriver against it in the teeth to tighten the chuck.
It slipped.
My knuckle went straight down onto the edge of the auger and sliced straight through. I didnt realise the edges were as sharp as the end.
It isnt a long cut but in the first instant I looked into it and saw three layers of flesh, brown then white then pink. then the blood flowed.
Dumb is dumb, even with the power off. :-(