fat cat是老外常用的俚语，形容有钱、有势的人，也可以理解为大亨、大款、阔佬，如果对不熟的人说就带有些讽刺味道。

【例句】
After graduation he's become very successful and he's turned into a real fat cat.
毕业后，他很成功，变成一个非常有钱的人了。

Harry is very poor while his brother is a fat cat.
哈里很穷，而他的哥哥是个有钱人。