" Zip your lip "
Say nothing; keep your mouth shut. Often shortened to 'zip it'.
I saw Kevin put sneezing powder in the staff room but he told me to zip my lip about it or it would spoil the joke.
Where did it originate?:
, 1940s. Deriving from the allusion to closing a garment with a zipper.
Where is it used?:
Hear the idiom spoken: