“cry one's eye out”字面意思是“把某人的眼睛哭出来”，但是，它还可以表达“痛哭、痛哭欲绝、表示某人心碎、伤心欲绝”的含义。

【例句】
The two heart-broken sisters cried their eyes out when they heard that their father had died in an accident. 
当得知她们的父亲死于了一场车祸，这两个心碎的姐妹痛哭不止。

What happened? Why is she crying her eyes out?
怎么了？她为什么这样痛哭流涕的？