I have a cat that seems to get upset every time I joke about giving him away. He won't even get near me and he won't let me carry him.
Do they, like, read our body languages or something?
Caveat: this is all based on my experience with cats.
They can learn to associate certain sounds (words) with particular concepts. My cats know what the words "feed the cats" mean. It's hard to say what their effective vocabulary is, but they do understand some words.
They are also very sensitive to tone of voice and body language - given how much of a cat's communication occurs via body language this is hardly surprising. Every cat I've lived with knew when it was being teased or laughed at, and all of them hated it (I think this is why people say cats are "proud" - they really do not like being teased or laughed at).
If I had to guess, I'd say that your cat recognizes from your body language and tone that
He doesn't like it.
(Oh, all the cats I've had figured out fairly quickly that "I'm sorry" means I'm trying to make up with them. I don't know how that translates to communications and mental states, but actually saying "I'm sorry" will get me forgiven (they stop avoiding me or shunning me) by the cat I offended faster than not saying it).
This is all based on my personal experiences with pets as well...
I'm off at college now but I have a couple of cats at my parents house that are "mine." They've shown to at least know when we are talking about them, and whether it's positive or negative. There was an incident when one of the cats had some, well, distressed anal glands, and he still gets visibly upset when we joke about that and call him "big pus butt"
On the note of dogs, Mine also show some indication that they know a bit of what we are talking about. I have a shepardy-mutt thing that doesn't like to be called "fat" (even in a loving voice) and a boarder collie that got embarrassed recently when I was recounting a story about her having poop stuck in her fur over the phone.
While it's not hard evidence, it is probably safe to say some pets have an idea when we are talking about them, and can probably deduce the tone. It'd be an interesting thing to study!
Interesting note, just as Kate Paulk said, "I'm sorry" gets me forgiven with my cats too, whether I stepped on them or offended them some other way. I think this may be based on body language primarily (and perhaps the words after they learn them?) as I either pick them up/pet them (if I stepped on them) or act guilty/put my head next to them where they're sitting (in the case I offended them)
No... they have not even the vaguest clue what you're talking about. They do not understand words and don't even want to try to understand words.
They do get sounds, tone of voice, body language. If you make consistent sounds and signals for some things they will learn those.
But you could say horrible things about them in a nice tone of voice and they would take it in a happy way. Likewise you could say nice things in a bad tone of voice and they would take it negatively.
This doesn't mean they can't learn or don't get concepts... just they have no interest in our language. One of my cats just made a territorial incursion (the basement is exclusively for my first two cats, the rest of the house is shared but the basement is "theirs") without too much signaling on my part I got her to leave quickly (without yelling, harsh tones, or any of that).