20 Celebrity Questions
Have one teenager think of a popular celebrity and have the others take turns to try to guess who it is by asking him questions. He may answer only "Yes" or "No." The guessers get a total of 20 questions. At any time, a player can use her turn to guess the celebrity.
Continue playing until each guest has a chance to think of a celebrity for others to guess. The winner is the player who guesses the most names correctly.
Crazy Wrap
Wrap a gift with a lot of wrapping paper and have the teens sit in a circle. Hand one teen the gift and start some music. The teen tries to unwrap the gift as quickly as possible before you stop the music. When you do, she must pass the gift to the next player, who continues unwrapping when you play the music. This continues until one player can get the last piece of wrap off the paper before the music stops. She gets to keep the gift.
Balloon Stomp
Blow up several balloons and give one to each teen. Have them tie the balloons to their ankle. Say "Go" and have the players try to keep their balloons from being popped while they try to pop everyone else's. The last player with an inflated balloon around his ankle is the winner. You can have them tie two balloons--one for each ankle--to make for a longer game.