punch someone's lights out

/P AH1 N CH S AH0 M W AH0 N EH0 S L AY0 T S AW0 T/
verb
  1. 1

    To give someone a serious beating using one's fists; to punch someone until he or she is unconscious.

Source: https://en.wiktionary.org/wiki/punch%20someone's%20lights%20out