How To Freak Out The Cat...
While the cat is upstairs, sound asleep, rearrange all the furniture. Move something big from one room into the other, stick a piano in the hallway, and then sit back and wait for him to come down.
He'll think he moved again.
He'll be upset.
But it will give him something to do the rest of the day - slink around on his belly, eyes wide, making sure that all his toys are there and that when we moved while he was sleeping, no one misplaced the food.