When somebody (usually a girl or gay guy) has a breakup and they have a slumber party with one or a few close friends where they eat tonnes of icecream and fatty foods and bitch about their ex's or let out their emotions.
Amy: "Nicola...me and Jace broke up."
Nicola: "Oh my god are you ok? Thats it I'm coming over and were having a Breakup party
, i'll get the icecream."