A tosser who has become so intolerable, that douchebag is no longer adequate to describe their level of douche.
Generally speaking, one is a douchebag before they graduate to douchebucket, but some losers can go straight to bucket level (See: @ChrislHayes)
Smitty: Dude, I smashed my brand new flat screen with a brick!
Leroy: Why da fuck did you do dat?
Smitty: I was watching MSLSD and that little twerp in woman's glasses was yammering and I lost it.
Leroy; That muhfuh is a douchebucket.
