My teenage kids have just started playing a game that they learned about from one of those Facebook sharing exercises, an answer to the question "what is the silliest game you and your friends used to play?"
It goes like this: in a group of people, one will put his hand to his ear, Secret Service-style. When other people notice, they will do the same, until there is only one person left who does not have his hand to his ear. Then they jump that person and wrestle him to the ground, shouting "Get down, Mr. President!"