NASA employee Mark Rober has come up with a fantastic Halloween costume that uses two iPads to create an amazing effect. He positioned one iPad 2 under his shirt on his front and one on his back. He then cut out two holes in his shirt around the iPads and added some fake blood around the openings.
Now this is the clever part, he setup a FaceTime call between the two iPads. The iPad 2 on his front shows what the iPad 2 on his back is seeing in its camera. This then creates the illusion that you can see right through his gut and out the other side!