“let one's hair down”直译为“把头发放下来”，但它所表达的真实意思是“ 放松下来，不再拘束，无拘无束”，它也可以用在朋友关系之间，意为“坦率一些”。

【例句】
I have been at home for a month, I need a place where we can let our hair down and enjoy ourselves.
我已经在家憋了一个月了，急需一个可以让我们无拘无束玩耍的地方。

He is really let his hair down and relaxed at the party.
他这‮在次‬派对上真‮卸的‬下了‮防心‬玩个痛。