Extended variation of 'slurry' - meaning a slut so dirty she is comparable to a bucket full of slurry - wet, mushy clay that resembles shit used in clay sculpturing to hold two pieces of dry clay together.
The female recipient of a man doing nothing other than to shoot a load of his jizz into her pussy and "get his rocks off." Essentially, a "fuck bucket" is simply a human sexual object, overwhelmingly female, who is nothing more than a receptacle for a man to "stick it in her" so he can get his rocks off. A very pejorative term applied to a woman.
Yeah, I been seein' Jill, but its only because I need to bust a nut and she's a good fuck bucket.
A boy who is, weird, boring, stupid, gross, ugly, has no friends, can't get a girl to have sex with him, thinks he's awesome when he's really just a loser, gets drunk a lot, is poor, his family hates him, he is a nobody.
Girl: eww! Look at that boy! He's such a bum bucket!