Noun has 1 sense

• scum bag(n = noun.person) bum, crumb, dirty dog, git, lowlife, puke, rat, rotter, skunk, so-and-so, stinker, stinkpot - a person who is deemed to be despicable or contemptible; "kill the rat"; "only a rotter would do that"; "the British call a contemptible person a `git'"; "throw the bum out"; "you cowardly little pukes!"