The cereal itself is a mixture of mashed maize (corn) and syrup, shaped into pieces that resemble barrels (of the sort that used to be a fixture of pre-ironclad sailing ships). The cereal is promoted by friendly old "Cap'n Crunch," a cartoon sea captain whose adventures revolve around the cereal. Cap'n Crunch's animated commercial adventures have given Quaker Oats the opportunity to spin off additional cereals based on the original, including Crunch Berries and Peanut Butter Crunch.
This vulnerability of the older phone call routing switches has long since been corrected by using separate circuits to transmit voice and signals, and by using more sensitive equipment, but it resulted in the Cap'n Crunch whistles becoming valued collector's items. Some hackers sometimes go by the handle "Captain Crunch" even today, as a result of this incident and 2600 The Hacker Quarterly is named after the frequency of the whistle.