Liar's poker is a bar game that combines statistical reasoning with bluffing, and is played with the eight-digit serial number of a dollar bill. The game is usually played with a stack of random bills from the cash register.

Rules

The object is to make the highest bid of a number that does not exceed the combined total held by all the players. If the first player bids three 6's, he is predicting there are at least three 6's among all the players, including himself. The next player can bid a higher number at that level (three 7's), any number at a higher level (four 5's) or challenge. The end of the game is reached when a player makes a bid that is challenged all around. If the bid is successful, he wins a dollar from each of the other players, but if it is unsuccessful, he loses a dollar to each of the other players.

Liar's Dice is a similar game played with dice, often as a drinking game.

The book

Liar's Poker is also the name of a book by Michael Lewis which tells of his time as a bond trader at Wall Street firm Salomon Brothers during the bond boom of the 1980s. The book takes its name from the game, which was popular with the traders (and played for stakes much higher than a dollar).