I love how this thread degrading into a discussion of drinking games. That said:
at least where I come from, Beirut and pong aren't the same. I play Beirut as a nonstop action game where there are no turns and there are two sets of cups, one for each person on a team. Once one person's cups are gone, they can't shoot. If a cup is made, that person can't shoot until they finish it. Same rule, if both balls are made consecutively by one team, your team gets one ball back. If you throw a ball and it hits the ground, you get it back. Pong is slower and takes longer. Drinking games and rules seem to vary by region anyway haha.
I play beer ball anyway, which is the best drinking game ever if you've got adequate space.