One of our cats, when she’s happy to see us, will literally fall down on her side, roll onto her back and curl her body in a “C” shape, her head around to the side. She usually says “mrrp” at the same time. She has always done this, since kittenhood, so I don’t think it’s anything she’s learned. Of course, she does get a scritch under the chin and soft talking when she does it, so we’ve certainly reinforced it.
I’m going to have to disagree. Any being willing and capable of shitting on my shoe with perfect timing and dead on accuracy has nothing to fear from me.
“Meow. Listen, monkey, we really need to have a talk about our relationship. Meow.”
Words to make one’s blood run cold… 
And I’ve just been rereading my Man-Kzin Wars books.
Nice monkey. Do not pet the Kzinti’s tummy.
Just to confirm the belly-up-as-defensive-aggressive thing, that position is the only way a cat can bring all its five weapons (mouth and paws) to bear simultaneously. Any attacker has the disadvantage of approaching with at least two paws still involved in locomotion and support, and they’re going to be the hind paws. The hind paws of a cat are much stronger and more deadly than the fore paws, so it’s an advantage to have them ready to use.
That’s an explanation I’ve heard that makes sense to me.
Okay, first let me say “cats are weird”.
Cats are not dogs, one thing we can all agree on is it is not a submissive posture. I think in most cases your average house cat does this to elicit attention from it’s pet human but sometimes the human mistakenly rubs the tummy or rubs the tummy too much and must be punished for taking liberties and not instinctively knowing when to stop. Bad human! Feel my pointy vengeance!
I remember seeing an article on feline behavior that showed several different facial expressions/ear positions and postures and what they meant. In some cases the difference was subtle. So I think that what most of you have said is right but there may are some subtle differences in the positions and expressions that change the meaning of the behavior from “pet me!” to “come closer so I can rip out your spleen!”. So you really have to judge on a cat by cat basis and do not choose poorly.
The cat wants attention. Nay… the cat is demanding attention. If you aren’t doing exactly what the cat wants then playful biting or pawing will ensue.
OR. he/she wants to play cat football, your call (look for goalposts).
I’m guessing the gesture of flopping down is a communication process. If they cat simply laid down in a casual manner it wouldn’t convey much information. The smackdown is a non-verbal gesture to get you to notice. There’s a good chance that a meow can be elicited if you cock your head sideways and say “what”?
Pet me, dammit!
In contrast to what **Hello Again ** is saying, and more in alignment of the above post, and, as a person who has literally had cat’s in the cradle from three month’s on in life: Cats upping their belly to their known human buddy is a sign of friendship, especially if they twist about playfully, and, like one of mine does, bite yer toes in the morning. If you engage them, they will then think " Yeah, PLAY, which involves some gentle play biting and bunny kicks, usually with claws not drawn out, so, play. That play indicates that you are part of their family group.
It’s not vengence, but simple cat play, they figure that if you get past their defenses, you are ready to play on their terms, and then up it a bit with the tooth and nail they are apt to. Mine react to:" No! too much claw! Fuck! Ouch!" and back off from it then. They can learn that, to my surprise.
I suppose to best sum it up, cat’s don’t roll on their belly with people they know to be submissive, but, rather, accepting.
Yeah, I was being facetious with the “feel my pointy vengeance!” stuff but who knows what thoughts are really going through their brains?
Mine does it because I have a telepathic forcefield that knocks all four-legged animals to the ground. I usually have to get really close to them (it’s a weak field). No, really, I do!
I didn’t realize it until just a few years ago, but every dog, cat, ferret, etc. just flops onto it’s back. It even works on small children who haven’t learned to walk yet. Yeah, I know what you’re thinking: “Well, what about the zoo? Do zebras and bears flop over?” Sometimes, but like I said, I have to get really close up to them–zoos won’t let me in that close. I don’t think the zookeepers want others to test their powers without knowing whether or not they have it.
You probably have this power too, just haven’t discovered it yet. . .
Tripler
. . . and you must only use your powers for good.
Your cat us undoubtely a a witches familiar.
She does this to entice you into reaching your hand down to rub her tummy so that she can tear your hand and arm to bloody shreds.
Beware.
My PJ is just like this. There is no way this is a defensive position, as his paws are in no way ready to attack. If I rub his tummy he will sprawl out even more so he clearly wants his tummy rubbed. This is definitely a position of completely being at ease in his surroundings. Maybe its not technically a submissive position but effectively it’s saying “your my owner, rub my tummy”. He does not do it for strangers that pass by.
Speaking of dog-like behavior, how many of you can take your kitty for a walk to the park without a leash?
I must have been communicating poorly, because Wile E’s post is pretty much what I was trying to say: while a belly-up position can mean many things (including but not limited to forms of aggression), the one thing it does not mean is “I submit to your superior social position within the group.” In other words, it is not a submissive behavior.
Fortunately my cat can counteract your witchie cat with pure goodness.
If you look close you can see the halo over her head. Likes her tummy rubbed too!
Goodness and niceness always conquers badness and not-so-niceness every time!
Hah. Have you ever been lulled into a false sense of security.
Seriously, people believe the damndest things. My neighbor inherited a real nice cat, all black by the way, from his son and daughter-in-law. They had a baby and the daughter-in-law insisted that cat had to go because, you know, they sometimes suck the baby’s breath away.
This explains alot, thanks for the science!!! 
Your cat looks just like our Pretty Black Girl. And she does that too. 