blivet

blivet /bliv'*t/ n.  [allegedly from a World War II
   military term meaning "ten pounds of manure in a five-pound bag"]
   1. An intractable problem.  2. A crucial piece of hardware that
   can't be fixed or replaced if it breaks.  3. A tool that has been
   hacked over by so many incompetent programmers that it has become
   an unmaintainable tissue of hacks.  4. An out-of-control but
   unkillable development effort.  5. An embarrassing bug that pops up
   during a customer demo.  6. In the subjargon of computer security
   specialists, a denial-of-service attack performed by hogging
   limited resources that have no access controls (for example, shared
   spool space on a multi-user system).

   This term has other meanings in other technical cultures; among
   experimental physicists and hardware engineers of various kinds it
   seems to mean any random object of unknown purpose (similar to
   hackish use of {frob}).  It has also been used to describe an
   amusing trick-the-eye drawing resembling a three-pronged fork that
   appears to depict a three-dimensional object until one realizes
   that the parts fit together in an impossible way.