The joys of writting error messages...
I once logged an error message in a program where it should not have been possible to get to. The message was "Committing seppuku! Arrrgggghhhhh!" followed by the program terminating. One of my fellow programmers on the team managed (somehow) to trigger it. He came to my desk, looked accusingly at me and said, "You wrote this, didn't you?" I had to allow as how I had, so we went over the code together to figure out how he'd managed to trigger the message.