Lots of beer
Two even teams
It basically starts out like quarters with a pitcher. The two teams square off over the pitcher and take turns trying to get the quarter into the pitcher by bouncing it off the table. When one team gets it in, the other has to drink. The non-drinking team for that round chooses the order in which the other team finishes the pitcher, designating the last man (or woman) as the anchorman. Each team member takes their turn drinking from the pitcher. Once their lips leave the pitcher, their turn is done. The anchorman must finish what remains. It works best with a team of 4 to 5. Drinkers and non-drinkers need to be spread-loaded evenly between the two teams.
The game is great because it relies heavily on teamwork. If someone can't drink everyone suffers. If the team isn't loyal to each other, the anchorman gets screwed everytime. Everyone has to pull their weight. You know you have good friends when you are the anchorman and never drink.
Always have a garbage can nearby. After all, there is no shame in puking.