First you find a big 5 floating in the fifth dimension and then you photograph it. All you need to do is find a six-foot invisible rabbit named Harvey to tell you where it is.
Actually, it is simply a stereo pair. The 5 is filled with the same background image and then offset in opposite directions. The image is key. It needs to be random enough so no one can see the figure in front of it, but not too random where the eye cannot see the figure when fusing the images.