shoot your mouth off

US /ʃuːt jʊər maʊθ ɔːf/
UK /ʃuːt jʊər maʊθ ɔːf/
"shoot your mouth off" picture
1.

입이 가볍다, 입방정 떨다

to talk too much, especially in a boastful or indiscreet way

:
He tends to shoot his mouth off after a few drinks.
그는 술 몇 잔 마시면 입이 가벼워지는 경향이 있어.
Don't shoot your mouth off about the surprise party.
깜짝 파티에 대해 입방정 떨지 마.