"The Flop" is a dance created by the Do the Flop Guy where everyone does a face-plant in sync with him when he shouts, "EVERYBODY DO THE FLOP!" The dance eventually ends the world.
The Do the Flop Guy (Dougal Flopguy) somehow "accidentally" jumped in the air while tripping and had the bright (and I mean BRIGHT) idea to shout, "Everybody do the flop!" and so everyone else followed.
The Do the Flop Song premiered on YouTube on January 7, 2014.