From Brewer's Dictionary of Phrase and Fable:
Cock-a-hoop or Cock-a-houp. To sit cock-a-houp. Boastful, defiant, like a game cock with his houpe or crest erect; eagerly expectant. (French, coq à huppe.)


“And having routed a whole troop,
With victory was cock-a-hoop.”
Butler: Hudibras, i. 3.