Psycho cat

I just noticed that a few people here seem to like/know stuff about cats and so thought that maybe one of ye could explain something to me. First of all I have to point out that I am 100% a 'dog person'. I love dogs. Growing up my grandparents always had 2/3 dogs at anyone stage. Then as a teenager my family adopted a pup from the pound, we inherited one of my granny's dogs and also kept a stray that we found, so for many years we had three dogs running around the house/garden. I have never liked cats, don't like their disinterested, aloof, don't care-ish attitudes. Don't like their scratchy licks and sharp claws. So to get to the point, I was in a friend's flat the other night and her flatmates cat came slithering into the room. I paid it no attention. If it had been a dog I would have been down on the floor playing with it immediately but it was a cat so I ignored it. Next thing I knew the thing had jumped up on my lap, circled around a few times then plonked itself down and went asleep, on MY lap!? My friend was quite surprised cos she said the cat wasn't usually that 'friendly'. I had my suspicions and didn't trust the cat for a second so I left it asleep where it was but didn't pet it. Next thing, suddenly, out of nowhere, the cat jumps up, stretches it's mouth back into a snarl and hisses at me then claws at my hand as I tried to shove it off the couch and runs out of the room. So my questions are firstly why did the cat come over and sit on my lap when it was obvious I didn't want it to, and why did it go psycho with no provocation?? Did it see that I didn't like it, want to win me over then get pissed off when I didn't play ball!? Do cats think that much??