" Tongue in cheek "
Meaning:
Humorously, not to be taken seriously.
Example:
Saying that I had drunk ten pints before the accident was meant to be ironic and tongue in cheek, unfortunately the police didn't see the joke.
Where did it originate?:
Britain, 19th century - in the works of Sir Walter Scott.
Where is it used?:
Hear the idiom spoken: