Notices

It would show a spoon on the screen, and with a combination of subtle thumb gesture and accelerometer gesture it would start to bend (not just back but in many directions like on that famous Matrix scene, if possible even apply the image from the front camera as reflection o the spoon), and as soon as the thumb leaves the screen or the gestures otherwise stop it would unbend back to normal.

The gestures need to be subtle enough that an observer would not be able to figure out how to do it by just watching (at least if they don't know what to look for) , and the animation should only start to happen after the gestures have been kept going for a small while to make it harder for people to find them via trial and error.