A glass of water is all that's needed to play some serious head games with your eyes.

This clip is a mere six seconds, yet we have no illusion it will make you scratch your head over and over.

Go ahead and watch. And then watch it again. And again. And again and again and again. Watch it until it you throw your hands up in the air and give up trying to figure out how it's done.

We'd love to meet the person who created this trick and ask him how he did it. Of course, he'd probably tell us a magician never reveals his secrets, which would frustrate us all over again.