You put your right foot out;
You put your right foot in,
And you shake it all about.
You do the Hokey-Pokey,
And you fall down on the ground.
That's what it's all about!
Cosplay (short for "costume play") is a somewhat geeky pastime in which people get dressed up as their favorite computer/anime/movie character. It's not my cup of tea, but it can be a quite time-consuming and elaborate activity for others, spending hundreds or even thousands of dollars on their hobby.
The fellow here is paying (was paying -- it's supposed to be an animated .gif, but for some reason I can't get it to upload) homage to QWOP, a Flash game called the "most difficult game ever created," in which you (attempt) to control a sprinter using the four keys to trigger his thighs and calves. It's something of a kinesiological mystery how they all work together.
At least it is to me. I don't think I've ever made it more than a couple of feet down the track.
You can play the original here.