Originally Posted by helene

Kids nowadays... I must be getting old!

It's an ancient form of secret communication called ROT-13 where you exchange each letter for the one 13 positions before/after in the alphabet (so encoding and decoding is the same, as long as you're using a 26 letter alphabet). Used to avoid revealing spoilers or to disguise offensive language in e-mail and on the Net -- old mail/news readers used to have an easily accessible ROT-13 function.