Elevator Pong is just like the video game Pong, but played with real elevators. In a building with two or more lifts, one half is designated the Left team and the other half the Right team (or Blue & Red, it's not important). If an odd number of elevators exist then the middle one is neutral. All the
elevators are linked to a central computer and their positions are tracked, as well as the position of the virtual ball.
The elevators act like paddles, which can hit and deflect the slow-moving virtual ball if they come in contact. If the ball makes it through all the opposition's shafts then that team scores a point.
In each elevator is a screen showing the current status of the game, scores, and where the ball is. As the only way to actually play the game is to move the elevator using the floor buttons, Elevator Pong acts mostly as a time-passing diversion. However if the lift you are riding in hist the ball you will hear a satisfying 'Bloop!"
*EDIT*
Or, with the power of the Internet, play against the building across the street, or on the other side of town!