Source : Free On-Line Dictionary of Computing

JRL
     
        {J. Random} Loser.  The names JRL and JRN were sometimes used
        as example names when discussing a kind of user ID used under
        {TOPS-10} and {WAITS}.  They were understood to be the
        initials of (fictitious) programmers named "J. Random Loser"
        and "J. Random Nerd".  For example, if one said "To log in,
        type log one comma jay are en" (that is, "log 1,JRN"), the
        listener would have understood that he should use his own
        computer ID in place of "JRN".