A Beater Boos, is a boy who is seemingly nice when first dated. This boy then becomes a big douche bag and cheats on his girlfriend. Beater Boos' are attracted to younger girls, specifically grade nine girls or younger, especially ones that are sluts. They are usually chubby chasers, getting turned on when their girl is able to scarf down two big macs in five minutes. A Beater Boos also likes to hit girls in the face for no apparent reason.
Dan: "Hey that guy just hit his fat girlfriend!"
Mike: "Dude, I know that girl, she gets around."
Dan: "Must be a Beater Boos."