run off at the mouth
US /rʌn ɔf æt ðə maʊθ/
UK /rʌn ɔf æt ðə maʊθ/

1.
banyak bicara, mengoceh, membocorkan rahasia
to talk too much, especially in a boastful or indiscreet way
:
•
He tends to run off at the mouth when he's had a few drinks.
Dia cenderung banyak bicara ketika dia sudah minum beberapa gelas.
•
Don't tell him your secrets; he'll just run off at the mouth to everyone.
Jangan ceritakan rahasiamu padanya; dia hanya akan mengoceh kepada semua orang.