- 守口如瓶 [shǒu kǒu rú píng]
- keep one's mouth shut as that of a jar; be as close as an oyster; be as silent as the grave; be buttoned up; be tight-mouthed; button [zip] one's lip; button up one's mouth; keep a still tongue in one's head; keep dumb as an oyster; keep [play] mum; keep one's lip buttoned; keep one's mouth closed [shut]; keep one's mouth tight as a jar lid; keep one's mouth tightly shut; keep one's tongue between one's teeth; never said a single word; stay tight-lipped:
John wanted to talk, but Mary told him to keep his lips buttoned. 约翰有意说出，但玛丽要他守口如瓶。
Disclosing that sort of information was very wrong of you. On such matters a doctor's lips should be sealed even to members of a patient's family.
She's very cagey about her past life.