Whopper

A "whopper" was a term for something unusually large, usually referring to a lie.

On hearing Leela talk, Jack Tyler commented that she didn't "half tell some whoppers," but Leela didn't know what whoppers were. (TV: Image of the Fendahl)

The Eleventh Doctor predicted that his oncoming "regeneration number thirteen" would be a whopper. (TV: The Time of the Doctor, Deep Breath)