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

muddie
 n.

    Syn. mudhead. More common in Great Britain, possibly because system
    administrators there like to mutter ?bloody muddies? when annoyed at the
    species.


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

muddie

    Synonym mudhead.  More common in Great Britain,
   possibly because system administrators there like to mutter
   "bloody muddies" when annoyed at the species.

   [Jargon File]