Cap'n Crunch Bo'sun Whistle, circa 1965

The Bo'sun Whistle was a prize included in Cap'n Crunch cereal boxes in the late-1960s. The cereal company didn't realize the whistles emitted a 2600hz tone--a sound that could trick telephone routing equipment into giving people free long-distance telephone calls. "Phone phreakers"--a group of pranksters that repurposed technology to infiltrate and test telephone system limits--prized these whistles.