1. Let one's hair down 放松，无拘束，坦率，无保留
After work, I always let my hair down and go out to a bar for a drink with my friends.
下班以后我喜欢轻松下来，和朋友一起去酒吧喝酒。
释义：从前西方女孩子外出前，都会把头发盘起来，以示庄重。只有回到家里才会卸下别针、头饰，让头发自然地垂着。所以，人们就用let one's hair down表示轻松一下了。
2. Let someone have it 让某人好看
Next time I see Rick, I'm going to let him have it.
下次我看到里克时要他好看。
