Proposition 1: buttered toast, if dropped, ALWAYS lands buttersidedown
Proposition 2: A cat, no matter from what height or in what manner airborne, will ALWAYS land on its feet
Conclusion: buttered toast when strapped on the back of a cat will end up hovering just above the beige carpet, revolving in a perpetual and self-cancelling spin!

I think it had been refined to take additional factors into account but.