Simple self-made Optical Illusion

To be honest, me and a friend had a beer or two yesterday night. Maybe that's why I got so excited about a little funny optical illusion I accidentally made while playing around with a piece of carton. The effect is the same as this cute little dragon shows, turning his head while you walk around him.

My version is a little bit simpler... :D Draw a square on a piece of paper with diagonal, horizontal and a vertical lines, cut it out and fold it along the lines, so that the lines are inside:

Now flip it over like this and try to imagine that you are looking at the top of a pyramid from above (like on the right image above).

Move your head slightly and you might see the top of the pyramid following you. It can take a while to trick your brain. If it doesn't work for you, close an eye, try it on a plane surface without distracting objects, focus exactly on the "top" for a while and really imagine you're looking from above, then move your head slowly.