The Joker is commonly used as a bug.

A bug in poker is a limited form of wild card. Poker is a type of Card game in which players bet on the value of the card combination (" hand " in their possession by placing a bet into Card games, particularly Poker games may contain one or more cards designated as wild. One or both jokers are often added to the deck and played as bugs. The Joker is a special card found in most modern decks of Playing cards or a Mahjong tile in some Mahjong game sets

In draw poker played for high and pai gow poker, the bug is considered to be an ace, unless it can be used as a missing card to complete a straight or a flush, in which case it becomes the highest card which can complete the hand. This article refers to draw poker games Go here for poker terminology relating to drawing cards or drawing hands. Pai Gow poker (also called Double-hand poker) is an Americanized version of Pai Gow (in that it is played with Playing cards bearing Poker hand In Poker, players construct hands of five cards according to predetermined rules which vary according to the precise variant of poker being played In Poker, players construct hands of five cards according to predetermined rules which vary according to the precise variant of poker being played

• K-K-Joker-5-2 is a pair of kings with an ace kicker. A kicker, also called a side card, is a card in a Poker hand that does not itself take part in determining the rank of the hand but that may be used to
• A-A-Joker-9-4 is three aces.
• A♥ J♥ 8♥ 3♥ Joker is a flush, ace-king high, the bug becoming the K♥, even if another player holds the "real" K♥. (But see double-ace flush for a variant rule. Non-standard Poker hands are hands which are not recognized by official Poker rules but are created by house rules. )
• 7-6-5-4-Joker is an eight-high straight, the bug becoming an eight rather than a three since both complete the straight but the eight is higher.
• J♣ T♣ 8♣ 7♣ Joker is a straight flush, jack high, the bug becoming the 9♣.

In California lowball, the bug is the lowest unpaired card in a hand. Some forms of Poker, often called lowball, sometimes called low poker, reward poor poker hands (in the traditional sense For example in 8-6-4-3 plus the bug, the bug becomes an ace; in A-2-3-5 plus the bug, the bug becomes a four.

Holding the bug greatly increases the power of certain drawing hands. For example, playing for high, a natural four-straight such as Q-J-T-9 drawing one has nine outs to complete the hand, any king or eight or the bug. In a Poker game with more than one betting round an out is any unseen card that if drawn will improve a player's hand to one that is likely to win By contrast a four-straight including the bug can have as many as sixteen outs to complete the straight - Q-J-T-Joker can catch any ace, king, nine, or eight.