My head just might explode:
From shirt.woot.com.
Credit for this goes to ihasahotdog: the loldog blog (I can't believe I just wrote that). There are a bunch of other suggested captions there, which are all less good.
George Hart shows how to slice a bagel into two linked halves.
The surface of the cut is a Möbius strip with two twists. As Hart remarks, you can also cut a bagel where the cutting surface is a regular (one-twist) Möbius strip:
You can still get cream cheese into the cut, but it doesn't separate into two parts.