like a cat in hot bricks：

热砖头里的猫 ×

像热锅上的蚂蚁 √

例句：

He was like a cat in hot bricks before his driving test.

他面临驾驶考试，紧张得像热锅上的蚂蚁。 

2

a fat cat：

一只胖的猫 ×

大款 √

例句：

Not every girl dreams to marry a fat cat. 

并非每个女孩儿都梦想嫁个大款。

lead a dog's life