button your lip
button (one's) lip
To be quiet. Often used as an imperative. Hey, button your lip! We don't need to hear any more out of you today! Julie knew better than to speak up when her father was so angry, so she buttoned her lip for the moment.
button your lipINFORMAL
If you button your lip, you keep silent about something although you would really like to speak. He had the grace and good sense to button his lip, even though this clearly caused him personal pain. As I entered his sitting room, I started laughing and was met with an impatient glare. I hastily buttoned my lip. Note: If you tell someone to button it or button their lip, you are telling them rudely to be quiet. `What have I done to deserve this?' — `Just button it, Park,' the Chief said.