Joker premiered in 2019 with Joaquin Phoenix as Arthur Fleck, a failed comedian whose involuntary laughing condition became one of the film's defining traits. Phoenix developed the laugh from videos of people with pathological laughter and split it into distinct styles for different scenes. The film's success turned that cackle into a widely shared reaction clip online, especially on soundboards and in meme edits. It remains popular because it is instantly recognisable, even without visuals, and carries both comedy and menace in a single sound.