from
The Free On-line Dictionary of Computing (8 July 2008)
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".