The term "Jokerz" is used often when describing a gang that replicates the style and M.O. of the Joker either through their own actions or as the result of Joker Venom manipulation.
Batman Beyond (DCAU)
The Jokerz were a Gotham City street gang based on the Clown Prince of Crime. While the original Joker might had long since disappeared from Gotham, his spirit lived on inside these villainous hellions. Dressed in clown outfits and face paint, they especially enjoyed practical jokes that turn deadly and generally creating chaos. At least one of the Jokerz was observed engaging in vandalism and then attempting to extort money from anyone who he believed was amused by his antics. While the Jokerz were certainly a menace, their crimes were small and they were much more easily thwarted than their criminally insane, diabolically creative and resourceful namesake.
The Joker's Jokerz When the original Joker reappeared in Gotham City, he enlisted a group of Jokerz as his personal henchman, including the granddaughters of his old sidekick and groupie Harley Quinn. In the alternate future created by the villain Chronos, this group of Jokerz was recruited and physically altered to once again serve as a major villain's personal gang.
Gotham City Impostors
In the first-person shooter video game, Gotham City Imposters, "Jokerz" is the name of an army of criminals who dress up like the Joker. The game is played from the perspective of two teams each trying to kill the other: the "Bats," in which people dress up like Batman, and the "Jokerz," in which people dress up like Joker.
Costumes are not limited to the Joker's classic purple three-piece suit - they are entirely customizable with hundreds of combination possibilities to allow unique appearances, but still resembling the Joker.