1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

14.

15.

View this video on YouTube
The upside-down variation is featured prominently in the music video for Diplo's "Express Yourself". [WARNING: lots of rumpshakin']
Contest Page on Mad Decent's Site
maddecent.com
The page says that a winner would be announced on June 16th, but one has yet to be declared. [UPDATE: They've extended the contest a week]