1 deck of cards
1. Make a flat pyramid with the cards. You can either make the base 5 or 6 cards. After you make the pyramid, you share the remainding cards between players. Don't show anyone else your cards.
2. Flip over the 1st card in the bottom row of the pyramid. If you have the card, or wish to bluff that you have it, you can tell anyone else to drink for 1 second. The bottom row is one, second row is two, etc...
3. If an opponent thinks you have the card they can call "bullshit". If you fail to show them the card then you have to drink double, and if you do have the card that they called bullshit on, they have to drink double.
4. If you have more then one of the cards flipped over, multiply the amount the person has to drink by this number. For example if a four is turned over on the first row and you have two fours in your hand, then you could make someone drink two instead of the standard one for the first row.
Remember that you can pretend that you have the cards in Bullshit Pyramid even if you don't, to make people drink more.