JargonFile/entries/grue.txt

grue

n. [from archaic English verb for shudder , as with fear] The grue was
originated in the game Zork (Dave Lebling took the name from Jack Vance's
Dying Earth fantasies) and used in several other Infocom games as a hint
that you should perhaps look for a lamp, torch or some type of light source.
Wandering into a dark area would cause the game to prompt you, It is very
dark. If you continue you are likely to be eaten by a grue. If you failed to
locate a light source within the next couple of moves this would indeed be
the case. The grue, according to scholars of the Great Underground Empire,
is a sinister, lurking presence in the dark places of the earth. Its
favorite diet is either adventurers or enchanters, but its insatiable
appetite is tempered by its extreme fear of light. No grues have ever been
seen by the light of day, and only a few have been observed in their
underground lairs. Of those who have seen grues, few have survived their
fearsome jaws to tell the tale. Grues have sickly glowing fur, fish-mouthed
faces, sharp claws and fangs, and an uncontrollable tendency to slaver and
gurgle. They are certainly the most evil-tempered of all creatures; to say
they are touchy is a dangerous understatement. Sour as a grue is a common
expression, even among grues themselves. All this folklore is widely known
among hackers.