Have you ever found yourself looking at one spot for more than 10 seconds? And noticed how that certain "something" you were looking at doesn't look so usual as it used to before? If you haven't, just try to use your imagination, the way you used to when you were a child and, yeah, you don't really have to be a child to find them ;) To prove I'm right, I'll show you how some real grown-ups did it.Here is the complete gallery.
Here is the complete set of photos at Flickr: Link | Link | Link | Link | Link | Link | Link | Link | Link.
Real Optical Illusion.
Cool Counter Illusions.
Print Ads Using Illusions.