Acronym for "Gay until pussy available", it refers to an opportunist "straight" or bisexual man that is willing to take advantage of other men for sexual purposes, often fooling them into starting relationships that will break once they have the smallest opportunity with a female.
To drive a gu patrol you must have at least a 3 inch straight through exhaust to compensate for your penis size. Usually seen on instagram posts labelled 'stolen' , or on the side of the road with hazards on because you've boiled the kettle driving down the highway.