Murphy’s Law, Finagle’s corollary:
“If something can go wrong, it will,
So if you throw a slice of toast with butter into the air, it will always fall with the buttered side down.”
Cats Conservation Law:
“A cat will always land on its feet.”
So, what would happen if we stick a slice of toast with butter to a cat’s back and we throw it to the air? The cat, by law, will land on its feet, but the toast, (by law too) will land on the butter’s side. Against this problem of physics laws, the nature chooses the best (and laziest, I think) way of taking a solution: the cat may just not fall.