ADJ-GRADED 故作上流人士姿态的;故充高雅的 If you describe someone as la-di-da, you mean that they have an upper-class way of behaving, which you think seems unnatural and is only done to impress people.
I wouldn't trust them in spite of all their la-di-da manners. 尽管他们处处显得很高雅的样子,我还是不相信他们。