I've had cats for many years. I've fostered over 50 cats. I should be somewhat knowledgeable about cats. But I'm not. This has been demonstrated to me by Simon and Sampson. These two boys are littermates, and they're teaching me many new things. First they started with the drooling and wiping their drool on my face. That was new, and I learned it meant they liked me. Great. Then there was this other behavior that was new to me as well.
So I asked a cat-savvy friend what it meant when Simon or Sampson would grab his brother's neck in his mouth, bite down, stand over him and start kneading and purring loudly. I thought it was weird but cute. Then my friend told me it was mating behavior. Ewwwwwwwwww. Sometimes I think I'm better off NOT knowing anything about cat behavior.
There is one other thing that Sampson does that I have not seen before. He carries stuffies (stuffed animals) around the house. They end up on the floor, on the bed, or in the shower. I don't know what he does with them. We've recently adopted a "Don't Ask, Don't Tell" policy around my house. It's better that way.