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

slopsucker
 /slop'suhk?r/, n.

    A lowest-priority task that waits around until everything else has ?had its
    fill? of machine resources. Only when the machine would otherwise be idle
    is the task allowed to `?suck up the slop?. Also called a hungry puppy or
    bottom feeder. One common variety of slopsucker hunts for large prime
    numbers. Compare background.


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

slopsucker
bottom feeder

   /slop'suhk-r/ A lowest-priority task that only runs when the
   computer would otherwise be idle.  Also called a "hungry
   puppy" or "bottom feeder" (after the fishermen's and
   naturalists' term for finny creatures who subsist on the
   primordial ooze).

   One common variety of slopsucker hunts for large prime
   numbers.

   Compare background.

   [Jargon File]

   (2003-09-29)