And then I guess the last thing I do is let my hair down.

然后我想我做的最后一件事就是放下头发。

I let my hair down at work all the time.

(字面意思: 把头发放下来)我一直把头发放下来的。

I had offered, but they both insisted I should 'let my hair down' on my birthday.

我提出过，但他们都坚持我应该在生日那天“放下头发” 。