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

SMOP
 /S?M?O?P/, n.

    [Simple (or Small) Matter of Programming]

    1. A piece of code, not yet written, whose anticipated length is
    significantly greater than its complexity. Used to refer to a program that
    could obviously be written, but is not worth the trouble. Also used
    ironically to imply that a difficult problem can be easily solved because a
    program can be written to do it; the irony is that it is very clear that
    writing such a program will be a great deal of work. ?It's easy to enhance
    a FORTRAN compiler to compile COBOL as well; it's just a SMOP.?

    2. Often used ironically by the intended victim when a suggestion for a
    program is made which seems easy to the suggester, but is obviously (to the
    victim) a lot of work. Compare minor detail.


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

SMOP

   /S-M-O-P/ [Simple (or Small) Matter of Programming] 1. A piece
   of code, not yet written, whose anticipated length is
   significantly greater than its complexity.  Used to refer to a
   program that could obviously be written, but is not worth the
   trouble.  Also used ironically to imply that a difficult
   problem can be easily solved because a program can be written
   to do it; the irony is that it is very clear that writing such
   a program will be a great deal of work.  "It's easy to enhance
   a Fortran compiler to compile COBOL as well; it's just an
   SMOP."  2. Often used ironically by the intended victim when a
   suggestion for a program is made which seems easy to the
   suggester, but is obviously (to the victim) a lot of work.

   [Jargon File]