walls have ears 隔墙有耳

“隔墙有耳”，汉语成语，意思是隔着一道墙，也有人偷听（someone may be listening on the other side of the wall）。比喻即使秘密商量，别人也可能知道，也用于劝人说话小心，免得泄露。与英文谚语“walls have ears”意思相同，表示“somebody may be listening, so be careful what you say”。

例句：

别在这里聊生意上的事情，隔墙有耳。

Don't say anything about our business dealings in here. Walls have ears.

你最好小点声，要知道隔墙有耳。

You'd better keep your voice down. Walls have ears, you know.