The phrase 'Tongue-in-Cheek' is used to imply that a statement is not seriously intended.
Example of Use: “After waiting in line for thirty minutes, I failed to appreciate the clerk’s tongue-in-cheek comment regarding bothersome customers.”
To put one’s tongue into one’s cheek was formerly a nonverbal method of expressing contempt. By 1842, the expression as well as the phrase acquired their contemporary meaning, indicating that a statement should not be taken seriously.