Instant Contradiction

The joke that "managed" to still be "funny" after thousands of tellings.

When someone makes a statement, usually in response to another character, then immediately proves their own statement to be false by idiotically or hypocritically disproving it. As this is a form of Ironic Comedy, it's supposed to be funny since it goes against what this person said Three Seconds Ago, but after it became a Ded Joke and an Eye Roll UnTrash, it lost its humor.