I have done this. It does work. Nothing bad happened, nor good (in the sense of hot witches showing up), but it was pretty fun trying it on other people too. I have no idea how it works, though I have to believe it's all in the head.
And I found a video for those who don't understand or would just like to see: http://www.youtube.com/watch?v=1aVHEab0sG8
Edit: I fixed the link.