Goldman's Christmas celebration rules have a funny condition: they can't hang out in groups of twelve or more.

The Business Insider wrote about the voicemail all Goldman Sachs employees received earlier this month. They were told not to organize small parties even if no firm money goes to pay for them.

By "small," Goldman means exactly twelve. Starting tomorrow, they can hang out outside of Goldman in groups of eleven, but not twelve.

The rule is set to stay in place for the month of December. Why? The firm believes that it would be inappropriate for its employees to be seen partying while the economy is still shaky and unemployment is high.

Twelve might be a good cut off because it's a very Christmas-y number. Twelve is also the number of the apocalypse (supposedly December 21, 2012), but since there are "Twelve Days of Christmas," it's probably more about that.

December doesn't start until tomorrow, so party it up tonight!