Caps was always my favorite. 2 teams of 2 sit on the ground about 15 feet or so away from each other, with a cup full of beer right in front of them. Get a bunch of beer caps, and the teams take turns trying to sink a cap into the other team's cup. When that is done the other team gets a "rebuttal" attempt, where if they make it it is like nothing happened. If the rebuttal misses, someone from the losing team (take turns) has to chug the beer, and the team that made it gets a point.
If a throw hits off the rim, the other team has to take a big drink out of their beer (not the cup, the beer in their hand).
Play to 10, win by 2. Good time.