You set up a table and on each side of the table is a triangle of cups filled with a small amount of beer in each cup. Two teams of two people each take turns throwing ping pong balls into the opponet's cups. If you make it in their cup, they have to drink it and vice-versa. That's the jist of it, but like many things...there is a TON of variations and rules all depending on who and where you're playing.