GABAGE: (adj) to exhibit qualities that are related to garbage, and also to have no other redeeming qualities in that particularskill other than illegitimacy.
A very average girl who gets treated like trash and some people feel bad for her. Many garbage girls developer superiority complexes to conceal feeling of inferiority.
Guy 1: Why do you like her bro? She’s a Garbage Girl. You can do way better.
Guy 2: IDK she makes me feel like I can’t do better.
I'll be in the garage is a reference to the show "Rick and Morty where rick and his lover call it off. He gets home and tells his family how life is meaningless and says I'll be in the garage, where he has a attempt of suicide.
Jake: Are you okay dude? That break up was pretty harsh.