slack ass

plural slack asses

1. CanadaUSslangvulgarSomeone who is exceptionally lazy, careless, or irresponsible in their work or duties.

   What's that? You want your slack ass in stockade?

   2009, Pope, Liston, chapter 22, in Manifest Oedipus. America at war, page 814

   2 more examples

   “It’s nothing to grin about, you slack ass,” Hopkinson snapped.

   1937, Compton Mackenzie, The East Wind Of Love, page 64

   So when the rich taxpayer from the Uplands phones in a complaint about the slack-ass sitting on the curb beside his paint can with his nose in a book, it's decided I've finally stepped over the line, and I'm fired.

   2008, Stevenson, Richard, Wiser Pills, page 53