You don't exist. Go away.
This Error Reference applies to:
All
This Error Reference is intended for:
Any audience.
This is not a viral infection.
It comes from programs like write, talk, and wall, if your invoking UID doesn't correspond to a valid user (probably due to /etc/passwd being corrupted), or if the session (pseudoterminal, specifically) you're using isn't properly registered in the utmp file (probably because you invoked it in a funny way).
