When someone gets ridiculously wasted (high, drunk, etc.), so much so that they look disgusting and not at all like they are having fun. Usually they wind up looking dirty, greasy, possibly lecherous or like they just got out of a coma (eyes rolling back, etc.).
I'm kind of worried--Keith isn't just wasted, he's dirty-wasted. I'm not sure if he even knows where he is and he looks like shit.