The line comes from Batman Begins, the 2005 film that rebooted the character with Christian Bale in the title role. In the scene, Batman hangs a corrupt police officer upside down from a rooftop and repeatedly demands that he swear to tell him where the drugs are going. The growled delivery became one of the film's most quoted moments, and clips of it spread through forums, video edits and soundboards as a shorthand for a serious interrogation. It remains popular because the line works both straight, as a dramatic threat, and ironically, when applied to trivial arguments.