The classic Usenet cipher - encode and decode are the same operation!
💩 About ROT13:
ROT13 ("rotate by 13 places") is a simple letter substitution cipher that replaces each letter with the letter 13 positions after it in the alphabet.
Because the alphabet has 26 letters, applying ROT13 twice returns the original text. It's self-inverse!
Fun fact: ROT13 was used on Usenet to hide spoilers and punchlines. Now you can hide your poop jokes!