I began my search for the origin and meaning of cock-a-hoop at dictionary.com, but they didn't have it and gave me a list of what theythought were likely links. One of those links led me to The Word Detective's blog where a full explanation is given which is quite interesting to read. Apparently the most common meanings in use today indicate either extreme happiness or extreme drunkenness.
A search for huzzah also sent me through various links, until reference.com said that according to the Oxford English Dictionary, Huzzah was a cheer with no apparent source. It's been in use at least since the time of Shakespeare. That's 500 years, give or take, so it's understandable that the origins have been forgotten.
So, as most of my readers celebrate the 236th anniversary of American Independence tomorrow, join with me in a loud Huzzah! And whether your idea of a good time includes extreme joy or extreme drunkenness, I hope you get all cock-a-hoop.