1. An action committed by an individual, either on purpose or not, that goes against the feel of the party or bar atmosphere.
2. To spill an alcoholic drink.

Something socially unacceptable done in a social gathering.

Something that goes wrong at a party.

Often when someone spills or breaks or drops something at a party (often resulting in a mess or general spectacle), or when someone does something embarassing or dumb.

Usually accompanied by someone actually yelling, "Party Foul!" while everyone else laughs because they're drunk.

The new catchy catch phrase that everyone is just itching to use! Someone drops their drink? Be sure to be the quickest to blurt out "OHHH, PARTY FOUL" and you win extra cool points with all the ladies, and possibly the men too! Practice being quick off the mark by dropping glasses in your own home! Try to train yourself to say it reflexively on hearing the glass shatter! Then open your wrists with a shard from that glass and try again! Repeat until dead!

when someone fucks up at a party by dropping beer or breaking something or falling.

An incident at a party that disrupts the flow.

A moment during a social gathering when one does something embarrassing and/or stupid.