Halliday was alluding to a famous ’70s hacker named John Draper, better known by the alias Captain Crunch. Draper was one of the first phone phreaks, and he was famous for discovering that the toy plastic whistles found as prizes in boxes of Cap’n Crunch cereal could be used to make free long-distance phone calls, because they emitted a 2600-hertz tone that tricked the old analog phone system into giving you free access to the line.