Thanks but no thanks.

We use this expression to decline an offer someone has made, or to give a negative opinion of something we don't want to or wouldn't want to do.

我们用这个表达来拒绝别人的提议，或者对我们不想做或不想做的事情给出否定的意见。

A:We're going to the cinema. Do you want to come with us?

我们要去看电影。你想和我们一起去吗

B: Thanks but no thanks. I've got something planned.

你的好意我心领了，但是我有别的安排了。