Don’t play dumb with me.别跟我装傻。

dumb 哑的；愚蠢的

play dumb 装作不知情；装傻，装聋作哑

Don’t play dumb with me, I know you know it. Just tell me！别跟我装傻，我知道你知道这事，赶紧告诉我！

I don’t want him to know that you are back, so I'm just going to play dumb the next time I see him.我不想让他知道你回来了，所以下次见到他我就跟他装傻。