Keep Talking
Thanks very much to Ralph Oborn, who sent me this game!
Break the group into pairs. On "go", each person must talk as fast and long as possible. The person who lasts the longest wins the round and moves up to compete with a winner from another pair. The process is repeated until a champion is crowned. Some ground rules: brief breaths are allowed, but no pauses. No lists or counting. No repeats. To make the game more difficult, you could assign a specific topic that the pairs have to talk about each round.
This one is exhausting just thinking about it!