This is a paper model dragon, whose head follows you around the room (sorry for the jerky vid, but I wanted to do an animated gif rather than an avi, since it doesn't need anything special to see it)

Here's the template so you can make one yourself.

It only works if you close one eye, and even this it's a bit tricky - a bit like those pictures you're supposed to look *'through* before you see the 3D image, although this isn't as hard as that. The easiest way is to shut both eyes, and then open one - if you start with both your eyes open, and shut one eye, it tends not to fool the brain...

*update* If you stand far enough away (more than 6 feet say), it works with both eyes open. And also, this isn't my design, I found it floating on the web somewhere...