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A chumsquare is a friend of yours who's pretty average. You know what kind of a day you're likely to spend with a chumsquare - nothing out of the blue or entertaining is likely to happen.

Families of chumsquares are common (we're pretty sure the chumsquare gene is passed on) and they generally watch alot of television in silence.
RB: So is Finn going clubbing with us tonight or not?
TM: Nah, he's set on staying home and being a chumsquare.
by Tobuss February 08, 2011