DEADBEEF /ded-beef/ n. The hexadecimal word-fill pattern for freshly
   allocated memory under a number of IBM environments, including the
   RS/6000. Some modern debugging tools deliberately fill freed memory with
   this value as a way of converting {heisenbug}s into {Bohr bug}s. As in
   "Your program is DEADBEEF" (meaning gone, aborted, flushed from memory);
   if you start from an odd half-word boundary, of course, you have
   BEEFDEAD. See also the anecdote under {fool} and {dead beef attack}.


Source: The Jargon File