This is one of those "gee, lets get blasted" games invented after tireless rounds of other games. Very high buzz factor.
The cup is passed, containing a quarter and a die. The shaker shakes to the person next to her/him (the shakee). The shakee then calls heads or tails. If the shakee is correct, the shaker drinks once for each spot showing on the die (6 times if you roll a 6). If the shakee is wrong, s/he drinks that many times. Pretty simple game. Variation: use two dice.