There's an anime called The Melancholy of Haruhi Suzumiya (I haven't seen it) and in the closing credits there's a dance, which you can see above. Now lots of people have learned to do the dance in real life and of course they like to to take videos of themselves doing it:
Some are in YouTube's classic 'in my bedroom' style:
And then there is the flashmob group, here broken up by the Police:
Now, what should I do for Halloween this year?