Mum’s the word / 守口如瓶

Meaning (意思):

English: You must keep silent; don’t tell anyone the secret.

 必须保持沉默；不要告诉任何人这个秘密。

Don’t tell anyone about the surprise for Mr. Edward. Remember, mum’s the word.不要告诉任何人给爱德华先生的惊喜。记住，守口如瓶。

Origin (来源):English: Since at least 1350 “mum” has meant silent. The word itself sounds like a person trying to talk with her lips shut tight. “Mum’s the word” has been a popular expression since about 1700.

中文： 早在 1350 年以前，“mum”一词就表示沉默。这个词的发音就像一个人嘴唇紧闭时试图说话的样子。大约从 1700 年开始，“Mum’s the word”便成为一个流行的表达方式。