Get a life is an American English idiom usually intended as a taunt1. The phrase generally instructs its addressee to go out and make their way in the world, without being supported by outside sources such as parents or benefactors2. It may also be directed at someone who is perceived as boring or single-minded like morons3, to suggest they acquire some other, more practical interests or hobbies and get dates, find a job, move to their own house etc.
The phrase is also used against people who are viewed as officious or intermeddling in someone else's affairs. It is another way of saying Get your own life, or Stay out of my business.
Note:
Get a life是一个美国俗语，一般带有嘲弄的意味。意思是让他们接触世界，不要单纯依靠外部如爸爸妈妈的资助生活。也可以对头脑比较简单的人说，让他们进步更多兴趣、喜好、约会、找个工作、找到是我们的房屋等。
还有一种使用方法，可以对好插手其他人事情的人说，意思是还是管管你一个人吧。也可以说Get your own life或 Stay out of my business.