The experiment is predicated upon the following assumptions:
1). If you drop a piece of buttered toast, it will always land buttered-side down.
2). A falling cat will always land on its feet.
Therefore, to prove the existence of anti-gravtiy, strap a piece of buttered toast (butter side up) on the back of a cat. Hold the cat a few feet off the floor, and let him go. The buttered toast, which MUST land buttered-side down, will be counter-acted by the falling cat, which MUST land feet-first. Since both of these events cannot occur simultaneously, proponents of the theory believe the cat and the toast would simply spin in the air indefinitely.