Bullshit

Bullshit is absolutely one of the best drinking games of all time. The objective is to get rid of all of your cards, and call "bullshit" on anyone who may be bluffing.

Rules
Deal all cards. Multiple decks may be required depending on number of players. Objective: Get rid of all your cards first.

The player to the left of the dealer goes first. This player must put down one or more Aces. However, the player places the card(s) face down in the middle of the table and declares what they just played. (i.e. "One Ace!").

The next player must play 2's, the next player must play 3's, etc. until Kings are played, at which point it starts over again at Ace.

Here's the fun part: If a player does not have the required card denomination that they must play, they still have to play a card (or more than one). The idea is to play it and declare it so that the other players believe you. If any player believes that another player did not play the correct denomination of card, they shout "Bullshit!" and must check what that player played. You may also shout "Cheat!" if you're in a situation where swearing would be inappropriate.
 * If the accusing player is correct, the cheating player must pick up all the cards and drink.
 * If the accusing player is wrong, he/she must pick up all the cards and drink!

Play quickly degenerates into finger pointing fun.

Some extra rules:
 * If a player is accused of cheating, he can admit it and retrieve all the cards without allowing the accusing player to see what was actually played.
 * Any form of cheating is allowed, really. Cards up the sleeve, slipping in more cards than you declare, etc. However, any of these infractions are punishable offenses if you are caught, and of course you must pick up all the cards.

Play continues around the circle until someone runs out of cards. This person is the winner. All other players are the losers and must chug the rest of their drink