[RGSpincich]

Knees-up?

It's tame. From other sources, I gather it's just an informal gathering of people.

[cake_crumb]

"From other sources, I gather it's just an informal gathering of people."

With a term like "knees up" to describe it, sounds like it's as...err...INFORMAL as you can get.

[KarlInOhio]

From the Oxford English Dictionary

knees up, Mother Brown
A light-hearted popular song beginning thus; a popular dance in which the knees are vigorously raised to the accompaniment of the song. So ellipt., as knees-up n., spec. a lively party or gathering. Also occas. in extended uses.

[Fintan]

From other sources, I gather it's just an informal gathering of people.

Congratualtions. You've won "The Understatement of the Day" Award.