To become silent
keep one's mouth shut · shut one's mouth
1. To close; to close the entrances into
2. To obstruct.
3. To enclose; to confine; to imprison
4. To be silent; to hold one's tongue
be quiet · belt up · button up · clam up · close up · dummy up · hush · hush up · keep mu · lock · lock away · lock in · lock up · put away · quieten · shut away · silence · still