A girl that is so greasy and nasty that the only place you could possibly do her is in a dumpster.
When fucking a dumpster fuck, it has to be in a trash can (a big green one) then you must immediately knock her out with your shoe or kill her with a trident.
A person who is so nasty, that after sex you have to wash yourself several times just to feel clean. (also alcohol is recommended)
Troy: Man, I got with a girl last night.
Brian: How was it?
Troy: I had to wash myself three times afterwards.
Brian: Ahh, you had yourself a dumpster fuck.
Troy: Do you have any Crown?
Brian: There isn't enough to help you now!!