Goggles let you see the world upside down or reversed
Ever wondered what it would be like to see the world upside-down? And no, just turning your head upside-down doesn't work. Well, anyhow, these goggles allow you to do just that. If seeing the ground above and the sky below is just a little too out-there for you, though, they can also be adjusted to let you see everything right-side-up, but reversed.
The Reversing Goggles consist of a ventilated plastic housing with an elastic head band, and two plexiglass prisms - one for each eye. In their regular configuration, these prisms will cause images viewed through them to appear upside-down. Rotating them 90 degrees, however, will instead reverse everything from left to right (and vice-versa).
There's no way of getting them to show you the world upside-down and reversed, which is, incidentally, the way that images are projected onto our retinas - our brains flip them over and turn them around.
While no practical use for the goggles comes to mind, the company selling them suggests that fun could be had trying to do things like shaking hands, writing, pouring water or walking around while wearing them. For God's sake, though, don't try driving with them.
Actually, according to experiments performed as long ago as 1896, if you wear such goggles for long enough, your brain will adapt and everything will appear right-side-up again.
Some assembly (including gluing) of the Reversing Goggles is required, which is perhaps a little questionable given their GBP 55 (US$86.90) price tag. If you only care about being able to see things upside-down, however, PsychKits offers a pair of fully-assembled Inversion Goggles for $25.