potluck

Short definition from Wiktionary

Noun

1. 1
   A meal, especially one offered to a guest, consisting of whatever food is available.
2. 2
   Whatever is available in a particular situation.
3. 3
   A shared meal consisting of whatever guests have brought (sometimes without prior arrangement); a potlatch; also, a dish of food brought to such a meal.
4. 4
   The last draft or portion of an alcoholic beverage in a pot or other drinking vessel.

Verb

1. 1
   To take part in a potluck, where each participant brings a meal to be shared by all.