Can you balance a belt off the end of your finger?
How about off the edge of a table?
This is a lesson in an object's center of gravity. When placed on a hook similar to this:
a stiff belt (make sure it's stiff, a floppy belt or rope won't work) will curve under, so its center or gravity is directly below the point where the hook meets your finger (or the table), causing it to balance.
Here's another picture of a hook - it doesn't have to be exactly the same shape as above. And here's one that doesn't even look like a hook, but it still works.