Source : Free On-Line Dictionary of Computing

Captain Crunch
     
        1.  ("Cap'n Crunch") An early 1970s
        {hacker}/{phreaker}/{phacker} who used a free whistle included
        with "Cap'n Crunch" breakfast cereal to fake pay phone system
        tones and make large quantities of free phone calls.  Also
        alludes to "{crunch}".
     
        {Home (http://www.well.com/user/crunch/)}.
     
        2. (After the above) {wardialer}.
     
        3. Reportedly, a program which {crash}es a computer by
        overloading the {interrupt} {stack}.
     
        (1998-08-25)