Anyone that knows a cat knows that they can warp space and time. You pass the cat, fast asleep in the sun downstairs. Three seconds later, you pass it again. Upstairs.
It didn't walk up the stairs with you. You didn't pass it on the way. Yet, here it is, staring at you, from the top step. How the hell did it manage to get upstairs so fast, past you, and manage to look like it's been sitting there for hours?
The answer is obvious. Cats are experts at trans-dimensional physics, and can create mini-wormholes to transport themselves anywhere they wish. The cat that was relaxing in the sun opened a wormhole to the top step upstairs, and was instantaneously transported to that step without having to move a muscle.
Why? I have no idea. The motives of cats are beyond me.