In real Beer Pong, the ball is not thrown. In the 1980s version played in Aeneas's and my basement, we used the paddles. Any loose ball was a free ball, and whoever recovered it got to serve. The paddles served as weapons. A hit to the outside your cup, and you had to take a drink. A shot into your cup, and you had to finish the beer. Normally played as doubles, each player had a full cup of beer in front of them, one paddle length from the end of the table. No goaltending allowed. Somewhere, there are official rules written up by us.