There appears to be a Cat Rule Handbook somewhere that all cats have read and memorized, by which they govern their existence, and we just have to put up with it.
1. There is no horizontal surface that cannot be slept upon. In fact, there are very few horizontal surfaces that are not vastly improved by the addition of a sleeping cat.
2. The mathematical formula for calculating the most inconvenient spot for a cat to be is :(h + c) / AsA x § = β. (Human + cat divided by "available surface area" times "human's desire to complete the task at hand" equals BINGO!)
3. Any and all cans being opened in the immediate vicinity could possibly contain tuna. Therefore, any and all cans being opened in the immediate vicinity are subject to urgent attention. Note: chick peas, which, on initial opening, can smell a lot like tuna, are NOT, they are vile impostors, and should be treated harshly.
4. All moving objects, especially human toes under a blanket at 4 a.m., are to be hunted and beat into submission immediately. Pursue the eyelids at your own peril, however.
5. A closed door is a challenge to be met and conquered.
6. Humans enjoy a tail tip up their nostrils, no matter what they say. So is purring at the same decibel level as a jet engine.
7. If one's dignity has been compromised, it is best to being licking oneself with an air of utmost purpose until the laughter has stopped. Then one must walk away, prominently displaying one's bum, with as much decorum as one can muster.
8. Preferred sleeping spots must be rotated on a semi-regular basis. One or two choice spots may be used in a habitual manner, but for maximum human confusion, chose random, unexpected areas for sleeping no more than one or two weeks at a time.
9. Deep, desperate meows that come from the belly should be reserved for dire situations, such as a ride in the car, an unexpected incarceration in the linen closet (arising from Rule #8) or the sudden suspicion that one is all alone in the universe.
10. Every box exists solely for your occupation. Even if a box is so small that all you can fit in it is your paw, you still, technically, occupy the box. After box occupation is established, you must now dismantle the box with your teeth.
I think I've covered most of the Rules of the Cat Handbook, I'm sure there are a few that elude me, like the mercurial rules governing washing (head first and work your way down? Sit first, then lie down?) and litter habits (cover the stuff only when there's no one there to notice?). I'll work on it, just as soon as I've moved the cat off the computer.