根据英文表达习惯，这两个网络走红术语，似乎应这样翻译：

犀利哥：Brother Sharp

淡定姐：Sister Calm

可参考英文网站：http://knowyourmeme.com/memes/brother-sharp-%E7%8A%80%E5%88%A9%E5%93%A5

About

Brother Sharp (犀利哥) is the nickname given to Chen Guorong, a homeless man from the streets of Ningbo in China’s Zhejiang province. The man became a national celebrity for his undoubtedly handsome face in February 2010 after a photograph of him wandering the streets was uploaded online. Eventually, the Chinese netizens tracked down and located the man through the means of Human Flesh Search Engine.

Origin

On the morning of January 30th, 2010, a photographer took his new Sony video camcorder to Tian Yi Square and decided to try out the new lens by shooting street scenes for the photography community forum Fengniao. The photographer, Mr. Tu, captured a few shots of a homeless man, who he said was “bearing dignification” as he walked down the busy streets.

“He has a very special temperament,” stated Mr. Tu, “so I couldn’t help but pick up the camera and take a few shots.” Later that day, Mr. Tu went home and sent his photos to the website, but did not expect to receive any significant attention.