It is well known that the brain can be tricked optically, by looking at strange patterns et cetera. I’ve seen quite some examples of that on the Internet already, but once in a while a real good one comes along. I found one where you have to look at for at least twenty seconds, longer is better. Just stare at the centre of the animation and then watch to objects around you. I haven’t seen such a good example yet where my brain really did some strange things to objects around me. Some bananas laying on the fruitdish grew and shrunk in size and a painting on the wall looked to be alive. I also read that you can really notice its happening in your brain, because if you close one eye and expose the other to the animation and then look around using your non-exposed eye, you will still notice the effect.
Anyway, if you got curious, give it a try yourself.