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

toy program
 n.

    1. One that can be readily comprehended; hence, a trivial program (compare
    noddy).

    2. One for which the effort of initial coding dominates the costs through
    its life cycle. See also noddy.


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

toy program

    1. A trivial program that can be readily
   comprehended.

   2. A program for which the effort of initial coding dominates
   the costs through its life cycle.

   See also noddy.

   (1996-05-19)