Comment Color Illusion (Score 2) 420
The XKCD plot just makes me see gold and white at different levels of brightness. But I did find this color illusion featuring yellow and blue. The dogs are actually the same color, which you see if you look at them individually through a small aperture
http://i.imgur.com/sh5NwCK.jpg
Make it pretty obvious that at some point your brain switches from wanting to see blue to wanting to see yellow based on the color context. It would appear some of us are slightly different in where transitions like that occur.