The sound comes from The Dark Knight, the 2008 Batman film in which Heath Ledger played the Joker, a criminal whose scarred smile and chaotic philosophy made him one of cinema's most quoted villains. The line and laugh circulated through YouTube edits, reaction videos and soundboards, where short clips of Ledger's performance became shorthand for mischief and menace. It remains popular because the performance is instantly recognisable even without visuals, and the laugh alone can set a darkly comic tone in seconds.