shut (someone's) bigmouth

Translations
заткнуть (чей-то) рот
He told them to shut their bigmouth before they got into trouble.
Он сказал им заткнуть рот, прежде чем они попадут в беду.
Definitions
To tell or force someone who is talking too much, especially in an annoying or boastful way, to be quiet or stop speaking.