luser: /loo'zr/ n. A {user}; esp. one who is also a {loser}.

:luser: /loo'zr/ n. A {user}; esp. one who is also a
{loser}. ({luser} and {loser} are pronounced
identically.) This word was coined around 1975 at MIT. Under
ITS, when you first walked up to a terminal at MIT and typed
Control-Z to get the computer's attention, it printed out some
status information, including how many people were already using
the computer; it might print "14 users", for example. Someone
thought it would be a great joke to patch the system to print
"14 losers" instead. There ensued a great controversy, as some
of the users didn't particularly want to be called losers to their
faces every time they used the computer. For a while several
hackers struggled covertly, each changing the message behind the
back of the others; any time you logged into the computer it was
even money whether it would say "users" or "losers". Finally,
someone tried the compromise "lusers", and it stuck. Later one
of the ITS machines supported `luser' as a request-for-help
command. ITS died the death in mid-1990, except as a museum piece;
the usage lives on, however, and the term `luser' is often seen
in program comments.
-- The AI Hackers Dictionary