Joker Poker is a game consisting of a normal pack of 52 playing cards with one joker, placed face down on a board. A person is chosen by a draw and given the opportunity to turn over one of the playing cards. If the joker comes up, the player usually wins a cash prize.
Typically though, the Joker is treated as a wild card which you can assign any value you wish. Scoring (hand ranking) is done identically to without wild cards, except that now 5 of a kind is possible, and that is the best hand. (5 deuces beats a royal flush, and 5 Aces is the best possible hand.)