Order 66 comes from Star Wars: Episode III - Revenge of the Sith, released in 2005, where Chancellor Palpatine uses the secret contingency order to command the clone army to execute their Jedi commanders. The order triggers the near-total destruction of the Jedi Order and marks the Republic's fall into the Empire. Online, the line and the moment became shorthand for sudden betrayal, often reused in edits, parodies and reaction videos whenever an alliance collapses. Its brevity and dark history keep it instantly recognisable to Star Wars fans and casual viewers alike.