conk1

 
Pronunciation: /kɒŋk/

verb

[no object] (conk out) informal
  • (of a machine) break down: my car conked out
  • (of a person) faint or go to sleep: he conked out on the rear seat
  • die: most creatures conk out smartly once they have passed on their genes

Origin:

First World War: of unknown origin