Origin

The picture originally came from a kid's Facebook profile, who goes by the name "Evan" and sometimes "Danger". He posted the photo after he got the Kinect system for Christmas.

Takeoff

The meme sprung up late December, 2010 after he posted a picture on Facebook of himself holding a Kinect system and making a weird face. It started to take off after variations were posted on Facebook, and then 4chan. It then began to pop up on various 4chan threads, mainly on /b/.

Mysterious Ass Face

In the full sized original photo, you can see a face behind his ass. People then began to assume his "derp" face came from a face giving him a "rim job" or "rusty trombone".