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An uncircumsized penis. The extra skin acts as a hat.
"I had to pull back Shawn's party hat to even tongue his tip when I was fellating him." Exclaimed Christine.
by PartyFavors.com December 04, 2008
This is given to an opposing player in the Halo videogame series when a plasma grenade is stuck to their head. The name originates from the blueish glow right before the grenade detonates.
Halo player 1: Here you go, a personal party hat just for you! *stick*

Halo player 2: Whah? *booom*
by CallMeNightmare April 22, 2009
poop in a Party hat and cum on the poop and put the hat on a person head and when they take the head off they will have the poop stuck on their head
Bob just gave Lucy a Party Hat.
by Stinky Rebel August 11, 2008
A VERY expencive item that you can buy on runescape for 5-30mil gp, (gold pieces) there are lots of different kinds of phats such as: pink, blue, white, purple, green, and just about any other color you can imagine, if you were a party hat to a drop party, people will drop cool stuff next to you, it was originally formed out of a "cristmas cracker" that you pull with anouther person that also has a cristmas cracker, and you would then each get a different colored phat!
Party hat's are very very expensive :D
by Kyle Biddle August 01, 2004