used in reference to the consumption of alcohol, legal or not. Most often used when you don't want everybody and their mom around you to know your plans for the night.
partypartyparty (also; party! party! party!) is a term used by an individual who's lifestyle encapsulates all that is chaotic and epic. Although alcohol may at times be involved, it is by no means necessary.
Partypartyparty is also commonly used as a universal cop-out or excuse for anything that is inexplicable, fitting all awkward (and non-awkward) scenarios.
Person A: "Hey man, why are you wearing a dress shoe and a Croc?"
Person B: "Because I partypartyparty."