the last straw

[英语俚语]忍耐的极限

Jack was always laughing at me in the presence of my classmates. But one day he insulted my mother. That was my last straw.

I struck him a heavy blow on the head.

杰克总是当着同学的面嘲笑我，但是有一天他竟辱骂我的母亲，我实在忍无可忍，给他头上重重一击。

注解：
the last straw源于“the straw that breaks the camel’s back”地根压断骆驼背的稻草，意指如果不断往骆驼背上添加东西，等到达到它所能承受的饱和点，这时哪怕再加一根稻草，也会把它压垮，喻指已到无法忍受的地步。

let one’s hair down

[俗]轻松一下；随随便便；毫无拘束

I hardly let my hair down in he presence of my would-be father-in-law.

在我未来的岳父面前我总是很拘束。

注解：
to let one’s hair down系指拿下发针，使头发垂落肩头，喻指除去表面装饰，使自己无拘无束、轻松、自然。