Cap’n Crunch hid a toy whistle that could phone the world for free.
Cover one of its two holes and the 1963 cereal-box whistle blew exactly 2,600 hertz — the tone AT&T used to control its phone lines. A hacker named John Draper, alias “Captain Crunch,” made the trick famous, and others built “blue boxes” to place free calls. Two of them, Steve Wozniak and Steve Jobs, sold their own — before starting Apple.
Cap’n Crunch on Brandseum