Heard this one from my Mom (RIP) about half-a-century or so ago:
There was a commotion in the machine shop, so the foreman puts down his coffee and donut, and walks over to investigate.
"What happened here?"
It seems one of the guys has cut off a finger.
"How the hell???"
"Dunno, really - I was just lining up the cut like this and --- Whoops! There goes another one!"
;-) Rich