Betty is a character in a Cartoon Network show called “Adventure Time”. She had first appeared in a picture in an episode. The staff of the show had confirmed an episode about Betty after she was first introduced. On January 30th, 2014, MSN.com published an episode titled “Betty”.
The MSN admins were having a conflict over the legitimacy of the episode. When the show’s fandom heard of the news, they started making memes relating the return of Betty on Tumblr. Users started calling it “Bettypocalypse”.