Tub means
tall ugly blonde. It's an acronym. There are a lot of these out there. Especially the ones that from the back look cool, and you're like, hey
maybe I'll pick up that
hottie. Then she turns around and you're just straight outta luck son.
Guy 1: "That blonde over there looks
awesome from behind - I'm trying to
get a look at her face"
Guy 2: "Yeah man, hope she doesn't
turn out to be a tub"
Guy 1: "Damn she turned around and she's totally a TUB!"