How many M&M candies can you fit inside a Klein bottle? Apparently, 547 M&M's. That's weird because Klein bottles [wiki] are supposed to have zero volume. And they're one-sided with no edges, to boot.
Link - via Cliff Pickover's Reality Carnival
Previously on Neatorama: World's Largest Klein Bottle
Now it's blindingly obvious that the candy is falling out left and right, as this insufficient surface can't possibly contain them. Alright, so it's not obvious. But picture a few points (drawn as dots all the same size) on a piece of paper, and surrounding them with one other dot. You get the idea.
Beajerry is of course right, it _appears_ to be an ordinary bottle with the spout connected to the side. But if it really was, how in the world would they have gotten the M&Ms in? Huh? Huh?
It's not too difficult to find pictures of unfilled bottles that let you see the entire topology, so I'll leave this as an exercise to the reader.
A Klein bottle is basically what would happen if you stretched a moebius strip so that ALL sides are connected, not just the two end strips. Of course, a 3D model isn't a true realization, because the hole through which the "spout" passes is a "cheat"--a true Klein bottle would be one continuous, uninterrupted shape--but is necessary for the bottle to exist as a tangible, three-dimensional object.
http://en.wikipedia.org/wiki/Klein_bottle
--TwoDragons
It just appears to be a simple bottle with a spout connected to one side.
However (and yes, this can be argued ad nauseum), the M&Ms aren't inside the bottle, nor are they outside. They're contained by the bottle yes, but since there is no true inside or outside saying that they're "in" the bottle is a bit backwards.