The Jargon File (version 4.4.7, 29 Dec 2003):

fandango on core
 n.

    [Unix/C hackers, from the Iberian dance] In C, a wild pointer that runs out
    of bounds, causing a core dump, or corrupts the malloc(3) arena in such
    a way as to cause mysterious failures later on, is sometimes said to have
    ?done a fandango on core?. On low-end personal machines without an MMU (or
    Windows boxes, which have an MMU but use it incompetently), this can
    corrupt the OS itself, causing massive lossage. Other frenetic dances, such
    as the cha-cha or the watusi, may be substituted. See aliasing bug, 
    precedence lossage, smash the stack, memory leak, memory smash, 
    overrun screw, core.


The Free On-line Dictionary of Computing (30 December 2018):

fandango on core

    (Unix/C, from the Mexican dance) In C,
   a wild pointer that runs out of bounds, causing a core dump,
   or corrupts the malloc arena in such a way as to cause
   mysterious failures later on, is sometimes said to have "done
   a fandango on core".  On low-end personal machines without an
   MMU, this can corrupt the operating system itself, causing
   massive lossage.  Other frenetic dances such as the rhumba,
   cha-cha, or watusi, may be substituted.

   See aliasing bug, precedence lossage, smash the stack,
   memory leak, memory smash, overrun screw, core.

   [Jargon File]

   (1994-12-16)