In what contexts can one use the phrase "哥只是个传说"?

or "妹只是个传说"?

 

In very relaxed contexts in which you can joke freely with your friends, you may say it, pretending to be cool.
Or on the Internet, in forums, online chatting and so on.
妹只是个传说 is extremely rare. In today's culture, 妹 stands for "cute girls", which doesn't fit too much the cool image of 传说中的哥...
The counterpart of 哥 is 姐, "elder sister", who sounds as strong as 哥. It makes more sense if it's 姐只是个传说.

 

But let's attend to the basic question first: "哥/姐只是个传说"
What is the sentence intended to mean?

 

Xiaolijie,it's just an internet slang,means" I'm the legend", and sounds pretty stupid to me, whatever the context is.

 

For the origin, you can see here.
http://zh.wikipedia.org/wiki/%E4%B8%8D%E8%A6%81%E8%BF%B7%E6%81%8B%E5%93%A5%EF%BC%8C%E5%93%A5%E5%8F%AA%E6%98%AF%E4%B8%AA%E4%BC%A0%E8%AF%B4

 

It also refers to a song which was ever popular with many young people.

 

full version: 不要迷恋哥，哥只是个传说

Your big bro me is just a legend, so don't just worship me. See here I use "just" twice in English to express some subtle complex originally in Chinese. I say don't worship me, but I mean the other way round.