The folks over at Cap'n Crunch just thought they were giving out fun little trinkets when they placed little bo'sun whistles inside their cereal boxes. What they were really dishing out were free long distance calls. Covering up one of whistle's holes would give the toy a frequency of 2600 HZ when blown and the prize could be used to hack the phone system. Imagine how many bo'sun whistles were thrown out in the 70s by parents who couldn't stand the noise. If only they knew the Cap'n was trying to cut their calling costs in half.