But thanks to my dearest new seatmate Ceszy Junsay (thanks Ceszy, you're a genius), she let me check out her book named 'Stereograms'.
Stereogram is an optical illusion of depth created from flat, two-dimensional image or images. Originally, stereogram referred to a pair of stereo images which could be viewed using a stereoscope. It is somewhat of an image that fools the brain, not the eye.
Here is one good example:
It was REALLY hard at first. It took me about 20 minutes before I can make that image above three by 'fooling my brain'. But once i got the hang of it, it was F-U-N! Until then I was able to see 3 dimensional images and I was like, WOW! :D
Here's another example. Hope you can find the butterfly here. You may actually click the image to enlarge it. Remember, cross eye, then relax. That's it :)
NOW THAT'S DEVIATION! Haha. More? Check out this link.