Pony Express! We had a party once where everyone wore western gear and was given a name tag that only had a number. The people there could then go to a part of the house and write notes anonymously to others to break the ice (To #14 from #38: Cute hat!
) Then the brothers would take turns delivering them to the people at the party, riding a broomstick horse (the Pony Express). Takes a lot of work, but it was one of the most memorable parties I've been to.