:rot13: /rot ther'teen/ [USENET: from `rotate alphabet
13 places'] n., v. The simple Caesar-cypher encryption that
replaces each English letter with the one 13 places forward or back
along the alphabet, so that "The butler did it!" becomes "Gur
ohgyre qvq vg!" Most USENET news reading and posting programs
include a rot13 feature. It is used to enclose the text in a
sealed wrapper that the reader must choose to open --- e.g., for
posting things that might offend some readers, or {spoiler}s. A
major advantage of rot13 over rot(N) for other N is
that it is self-inverse, so the same code can be used for encoding
and decoding.
-- The AI Hackers Dictionary
