cock-a-hoop [kok-uh-hoop, -hoop, kok-uh-hoop, -hoop]
1 Extremely and obviously pleased, especially about an achievement.
2 askew; out of kilter
Ireland will be cock-a-hoop after their big win against Wales, so they will come with plenty of confidence and swagger. (Mark Orders, The words from England boss Eddie Jones that could give Wales their team talk for big clash with old enemy, WalesOnline, November 2020)
I have much more important things on my mind, such as I have just got a 12 quid voucher from Waitrose out of the blue and I'm cock-a-hoop. (Zoe Williams, What are you desperate to do before another lockdown?, The Guardian, November 2020)
Her rosy picture of the future had been knocked cock-a-hoop, and insecurity crushed her usual optimism. What would become of her? (Patricia Rice, This Magic Moment)
It is love that has come - not as you imagined it, all cock-a-hoop with fine feathers, but sadly, with bleeding feet. (Agatha Christie, Murder on the Links)
This adjective is from the 16th-century phrase to set cock a hoop, to set (the) cock on (the) hoop, which apparently meant to turn on the tap and let the liquor flow prior to a drinking bout. The earliest attestation of this phrase is from A dialoge of comfort against tribulacion (published posthumously in London in 1553), by the English humanist and statesman Thomas More (1478-1535): "They haue founde out so easy a waye to heauen as to take no thoughte, but make mery, nor take no penaunce at all, but syt them downe & drynke well for our sauiours sake, set cocke a hope & fyll in al the cuppes at once & thā [= then] let Christes passion paye for all the shot. "
Mid 17th century from the phrase set cock a hoop, of unknown origin, apparently denoting the action of turning on the tap and allowing liquor to flow (prior to a drinking session). (Oxford Online Dictionary)