"Liar's Poker" is a betting game often associated with Wall Street traders. It involves wagering on the frequency of digits appearing in the serial numbers of U.S. paper currency.

In each round, players take turns proposing an ever-increasing number of digits (e.g., a sequence may involve: three 5s, three 6s, four 5s, etc.).

The game proceeds until somebody calls out the previous proposal as being a "lie." If such a sequence exists (e.g., there are four or more 5s between all the serial numbers held) the person who announced the proposal wins.