『 mum's the word』

　　保密，保守秘密

　　(图片来自网络，侵删)

　　释义：

　　见柯林斯英语词典

　　在英式英语中，mum 一词本身可作形容词，指keeping information to oneself; silent

　　例句：

　　Mum's the word, or the surprise party won't be a surprise.

　　In fact, mum's the word when it comes to talk of a transfer right now.