Royal
Navy slang
dating back before the Second World War, it means to defecate, crap, shit or take a dump. Nothing
fancy, to crimp off a length you merely have to evacuate your bowels.
"That fat fucker of a
stoker is getting shitty with me again!"
"What're you goin' to do?"
"Next time the
cunt is down the engine room, I'll crimp off a length in his best
boots!"