20 years ago I bought a used Mac Classic II (OS 7.5.3) from a private seller. One day I couldn't use it because the unknown-to-me password had somehow become invoked. I called a courier & sent it off to a place 100 km away where a fellow deciphered the password & wrote it down for me. It was sent back in working order with a note saying "your password is tluafed&troper."
Today I realised for the first time that it was the words report & default spelled backwards.