what a nerve 真不要脸；真不知耻；好大胆；脸皮真厚

【例句】
What a nerve! She just walked off with my radio!
脸皮真厚！她一声不吭把我的收音机拿走了！

What a diabolical nerve he has, coming in here like that!
他真不要脸，居然就那个样子来到这儿！