Buttered Toast + Cat = Antigravity

Timeless paradox...

"Cats always land on their feet.

Buttered toast always lands buttered-side-down.

The paradox arises when one considers a cat with a piece of buttered toast attached to its back. In that configuration, the cat would be unable to land on its feet without the toast landing buttered-side-up, and the toast would be unable to land buttered-side-down without the cat landing on its back."
- WikiPedia