Any mustache worn by a douchey guy that is unaccompanied by a goatee, side-burns, beard, or other facial adornment. Typically the cop mustache is found on overly aggressive men with short hair and small penises. This facial hair is most easily witnessed just after speeding in a car or urinating in public. Synonyms include: mini soup strainer, night stache, and molester mustache. Alternate spelling: cop moustache.