Using a Capt. Crunch whistle, you could recreate the tones telcoms used to initiate long distance calling. Meaning you could blow the whistle and get free long distance. http://en.wikipedia.org/wiki/John_Draper
It's a reference back to John Draper's work on the blue box. You could trick AT&T pay phones into thinking you had deposited money by playing tones which were reproducible on toys that came out of Captain Crunch boxes.
It's a plastic whistle, like the ones that were found in some cereal boxes forty years ago.
It emits a note at 2600Hz, which coincidentally was the frequency for carrier control on the Bell phone network at the time.
In the early early days of telephone hacking (phone phreaking) a guy named John Draper discovered that the toy whistle found in a box of Cap'n Crunch cereal would emit a tone at precisely 2600 Hz. This frequency was used by The Bell System to issue call routing instructions. With it, you could make free long-distance calls around the world. Some via satellite.