Joker — a poker slang term, most commonly meaning a wild card that can represent any other card in games where it is allowed.
Explanation. The Joker functions as a wild card in certain poker variants (such as home games, Five‑Card Draw, Pai Gow Poker, and some video poker), allowing a player to substitute it for any card that improves their hand—sometimes under specific rules, it acts as a “bug,” meaning it completes straights or flushes or counts as an ace otherwise.
Alternative slang usage: in Texas Hold’em, “jokers” can jokingly refer to a pair of Jacks as hole cards, but this is informal and rare in tournament or casino contexts.