bigmouth strikes again

Translations
болтун снова ударяет
He said he would keep the secret, but the bigmouth strikes again.
Он сказал, что сохранит секрет, но болтун снова ударяет.
Definitions
A phrase meaning someone has spoken out of turn, revealed a secret, or said something inappropriate or controversial, often causing trouble. It is also the title of a well-known song by the band The Smiths.