Cold Feet：to suddenly become too frightened to do something you had planned to do,especially something important such as getting married. (尤指面对结婚等重要事宜时)突然退缩，裹足不前.
Etymology：This expression appears to date from the nineteenth century, at least in its present meaning. In the early seventeenth century it was an Italian proverb that meant to have no money; it was so used by Ben Jonson in his play Volpone. The source of the more recent meaning is obscure. Some believe it comes from soldiers retreating in battle because their feet are frozen. Another source cites a German novel of 1862 in which a card player withdraws from a game because, he claims, his feet are cold.
中文释义：cold feet 用来表达某人因害怕胆怯而临阵退缩，打退堂鼓，缺乏自信或胆量，一般常常与 get/have 搭配，get / have cold feet突然退缩，裹足不前。引申几个和“feet”相关的俚语：have two left feet（跳舞时）笨手笨脚，手脚不协调；be back on your feet （病后）恢复健康，痊愈；think on your feet 思维敏捷，反应快；vote with (one’s) feet用退场来表示不赞成、不支持。