Board Thread:Fun and Games/@comment-25249743-20151104205705/@comment-25653892-20151104221506

Also, 'impossible colors. Those are colors that aren't in the visible color range, like a red brighter than white, a blue darker than black, or an orange more saturated than fully-saturated orange. We shouldn't be able to see any of these types of colors normally, but we can if we tire out our eyes or decieve our minds.

In the most extreme of cases, our brains can be coaxed into visualizing mud, the technical term for a reddish-green or yellowish-blue color. What that would even look like, most people don't know, as it's oxymoronic by definition. Only a handful of people, a small percentage of participants in certain studies, have been able to see mud at all. Apparently, it's kinda like looking at the purple for the first time.

tl;dr: That's not in our color space!