my lips are sealed
US /maɪ lɪps ɑr siːld/
UK /maɪ lɪps ɑr siːld/
1.
used to say that you will not tell anyone a secret
:
•
Don't worry, my lips are sealed. I won't tell anyone about your surprise party.
•
She asked me to keep it a secret, and I told her, 'My lips are sealed.'