A team stands at each end of a ping pong table with each person's cup full 'o beer on the table in front of them. Teams usually are two or three.
The cup must not be closer than the distance from the tip of your thumb to the tip of your pinky (fingers spread wide) from the edge of the table.
With ping pong ball in hand, each player (one at a time) tries to throw the ball into any opposing players' cup. Players can lean over the table as far as they can to close the distance.