Properties of shadows you can use to show friends an interesting joke. Of oiled paper arrange the screen; it is sufficient to tighten this paper square cutout in the sheet of cardboard. Behind the screen, place two lamps; the viewer will be sitting in front of him, on the other side. One lamp, for example, left, light.
Between a lamp and the screen, place on a wire oval piece of cardboard, and then appears on the screen, of course, the silhouette of the eggs. (Right lamp is not yet ignited.) Now you claim that will result in the “x-ray”, which you will find inside the egg... chicken! And indeed, after a moment, guests can see the silhouette of eggs like a lighter at the edges and in the middle of it emerges quite clearly that the silhouette of a chicken.
Solution focus is simple: you light right lamp on the path of the rays which placed a cardboard outline of a chicken. Part of the oval shade, which is in the shadow of “chick lit, right lamp, so the edges of the “eggs” lighter internal parts. The audience, sitting on the other side of the screen and unsuspecting of your actions, can, perhaps, if they are ignorant of physics and anatomy, is to imagine that you actually miss through a chicken egg x-rays.