[im2w1l]

I like this one http://0.media.collegehumor.cvcdn.com/70/36/483778211d5177e9...

It seems impossible a few seconds until the trick is revealed.

[dr_zoidberg]

I was expecting that (or the T-rex variation of) when he mentioned optical illusions. The image he posted is more related to perspective than how the visual cortex works -- that is, it can even be done inside a 3d game/engine, with clever texturing.