Joe Siegler's explanation of "Aardwolf":

"Call Apogee and say Aardwolf."  It's a sign that to this day is something
that I get asked about a lot.  This is a sign that appears on a wall in a
particularly nasty maze in Episode 2 Level 8 of Wolfenstein 3D.  The sign
was to be the goal in a contest Apogee was going to have, but almost
immediately after the game's release, a large amount of cheat and mapping
programs were released.  With these programs running around, we felt that
it would have been unfair to have the contest and award a prize.  The sign
was still left in the game, but in hindsight, probably should have been
taken out.  To this day, Apogee gets letters and phone calls and asking
what Aardwolf is, frequently with the question, "Has anyone seen this yet?"

Also, in a somewhat related issue, letters were shown after the highest score
in the score table in some revisions of the game.  These letters were to be
part of another contest that got scrapped before it got started, where we were
going to have people call in with their scores and tell us the code; we'd then
be able to verify their score.  However, with the cheat programs out there,
this got scrapped too.

Basically, "Aardwolf" and the letters mean nothing now.  Also note that if
you found the Aardwolf sign in the game (without cheating), there's a VERY
strong chance that you're stuck in there.  The only way out may be to restart,
or load a saved game from before you went into that maze.