famous last words

noun[usually plural]2

1. •
   A notable final utterance before death, especially one made by a celebrity or historical figure.

   • Lawrence died defending his vessel and his famous last words, "Don't give up the ship," have been familiar to every schoolboy. — 1908
2. •
   (figurative) A statement which is overly optimistic, results from overconfidence, or lacks realistic foresight.

   • Says one Sperry product executive: "As a manager, there is almost nothing you can do to get fired here." Considering the new circumstances, those could be famous last words. — 1986