It started as a nonsensical video with costumed people dancing to the Baauer song, "Harlem Shake":



These guys fine tuned it, making the solo masked dancer at the beginning standard:



Since then, it's been duplicated 20,000 times online and by Jimmy Fallon among others. Possibly the biggest version came from the rock duo Matt & Kim:



As a final statement, this is my favorite:



So what's next? Once it goes mainstream (which it kinda already has), it'll be considered dead.