A nickname for the biggest whore one knows. Just like Tyrannosaurus rex means "King of the terrible lizards", Skankasaurus rex means "Queen of the skanky-ass sluts".
Guy 1: Dude, I think I can get an easy fuck from Tanya at the party...
Guy 2: Man, for your own good, stay away from her infested ass! She's such a Skankasaurus rex!
A girl who is complete white trash. She is also unattractive, an attention whore, a slut, and any other combination of unbecoming qualities. Generally can be spotted in the local watering hole hitting on old skankymen in order to obtain free drinks.
That girl is such a skankasaurus rex she has sat on four old nasty laps in the past 15 minutes.