One of many all-purpose expletives comparable to fuck, shit, damn it or bloody hell, typically uttered when something surprising and/or undesirable has happened. It is considered to be more whimsical and socially acceptable than blatantly dropping the f-bomb in public.
Usage of "crapmonkey" as an expletive is believed to have originated in suburban New England.
"Crapmonkey! I just stabbed myself in the arm with a friggin' pencil. How'd that happen?"