When my cat is sitting on something I want to pick up, the command of choice is: "Puss Off." This works on several levels. For example, it is halfway between "push off" and another expression beginning with P and ending with "off."
Cats have an eerie ability to follow you from in front. This is to say, they can walk exactly one step ahead of you from one end of the house to the other. Sometimes this can be annoying, especially when (for example) you're in a hurry to go to the bathroom. The correct command for this situation is: "Kitty Up."