Wiktionary
whoop-ass
n. 1 (context figurative slang US English) An act of beating. 2 (context idiomatic slang US English) A fight. 3 (context figurative slang US English) strength or will to fight or compete. vb. 1 (context idiomatic slang US English) To beat or strike. 2 (context idiomatic slang US English) To defeat in a fight. 3 (context idiomatic slang US English) To defeat or excel against (someone) in a competitive event.