Puzzle Party
Name Tag
Once most of the players were at the party, I randomly distributed a small card to each one of them. On the front of the card were some number of shapes, written in a color, containing a letter of the alphabet. On the back were four clues, each clue describing a different member of their team.
Each person had a similar set of clues: one clue mentioned a color that a teammate had, one noted the shape, another noted the number of shapes on the card, and the last stated the letter. There was a unique solution, but the puzzle was not so dense as to have more than two people incorrectly get together without conflicts.
It only took about 10 minutes or so before everyone had pretty much figured out what team they were on. The last three people to arrive didn't even have to do any solving, as the teams had figured out exactly what this person would have.