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!"