Noun: The fat obtained from overindulging, typically in alcohol. It is likely the root of the freshman fifteen.

Adjective: Describes general bloating due to partying. Targeted areas include the stomach and cheeks, but long term partying can lead to an overall increase in body fat.
Girl 1: Does this dress look good on me?

Girl 2: ...looks a bit tight.

Girl 1: I wish I could lose my baby fat.

Girl 2: That's not baby fat, that's party fat. Quit going out every night and do some sit-ups, you're starting to look like a fat bitch.
by McSantos April 22, 2009
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A large house party that friends all attend, get drunk, smoke weed, listen to loud music, and laugh the night away!
Wanna come to this fat party at my buddy Alex's Saturday night?
by starlorde222 February 27, 2016
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