I’ve long been fascinated by blue boxes, small devices built in the 1960s and 70s to hijack the old analog phone systems for free calls.
The underground group of hackers and tinkerers behind this were dubbed phone phreaks. One leader of this group operated by the handle of Captain Crunch, as it was discovered a plastic toy whistle included in the cereal could generate a tone used to trick the phone system into allowing long-distance calls.