看美剧学英语俚语：Lose one's nerve

Fannie

Lose one's nerve: To no longer have the courage to do something，to become frightened or timid. For example, I wanted to ski down the expert slope but then I lost my nerve. This expression employs nerve in the sense of "courage or boldness." [Early 1900s]

中文释义："Lose one's nerve"短语中"nerve"一词通常指神经，然而它也有一个不为人所熟悉的意思“勇气，胆量”，所以"Lose one's nerve"意思是指某人不知所措，慌张，胆怯等。一般在美剧口语表达中出现比较频繁，表达说话者内心的紧张，害怕。引申几个和lose相关的短语:lose one's rags（冒火,暴跳如雷 ）；lose one's reason（失去理智,不讲道理,发疯）；lose one's temper（发脾气）；lose one's shirt（一无所有）；lose one's marbles（陷入疯狂）.

培青|SantaBarba

补充一个常用的：
lose face      现眼; 面上无光;