Chameleons' eyes rotate independently of one another, so the little lizards can actually sit still and see what's behind them and what's in front of them at the same time. Nifty.
Almost as nifty, any human who can cross their eyes can also make it look like they're crossing just one eye at a time. Impress your friends!
1) Cross your eyes.
2) Then, look really, REALLY hard to your right. (With both eyes.)
3) Cross your eyes again.
4) Look really, REALLY hard to your left.
I know this is silly as shit, but it's also sort of neat, especially if you're 11 years old, or you have to babysit, or you're on a reasonably bad date.