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1.
A turd, that someone has deposited in the toilets that are only for peeing in...
the "cookie" is referring to the turd.
Guy1: i was in the bathroom at wal-mart, and somone had left a fresh, steaming batch of urinal cookies!
Guy2: EWWW! Thats Nasty!
by Bubba2x4 October 07, 2009