Beer Pong is a drinking game that originates from Beirut, Lebanon. It was invented in the 1980's on a regular ping pong table, although beer pong does not necessarily need to be played on a ping pong table, but a table long enough to have a distance of 6 feet or more between the sets of cups.
The traditional style is a pyramid-scheme of 10 cups on each side, filling them with 2-3 12oz beers, with each side having a water cup to wash the balls. The game is usually played with 4 people although you can also play singles.
The object of the game is to toss a ping pong ball into your opponents cup, and if done so they must drink. There are many different varieties of beer pong, one of the most famous is shown in the movie Beerfest, called Paddle Pong, played with one cup and ping pong paddles.
For more information on beer pong game types or the official rules please check www.ponguniversity.com
I just spent 100$ creating my own beer pong table, it has a remote control that drops the table down from the ceiling which triggers spotlights and techno music.