Julius von Bismarck is a German guy who created a camera-gun that, when triggered by the flash of another camera, projects an image onto whatever the other camera is taking a picture of:

The Image Fulgurator is a device for physically manipulating photographs. It intervenes when a photo is being taken, without the photographer being able to detect anything. The manipulation is only visible on the photo afterwards.

So creepy and so outrageous. Easier to understand in the video below (via Gadget Lab):