Watch: Did Mr. Beast Buy the NFL? Viral YouTube Stunt ExplainedThe internet's new favorite slang term has some users scratching their heads. While the expression "67" (pronounced "six-seven") has surged in popularity on social media, the significance of the number remains a mystery to some. The term's origins have been traced back to the song "Doot Doot" by Skrilla, in which the rapper frequently recites the lyric, "Six-seven.