I have twin sister black cats called Chloe and Radcliffe (after the evil twin sisters in The League of Gentlemen).
They are a substitute for my dream pet. This is a very cheesy 80's Martini ad style fantasy pet - a black panther. I got to play with a domesticated one when I was at an aquarium (of all places) at the age of 10 (really) and I always wanted one after that.
You can't keep big cats anymore as far as I know. Not surprising really.
In Belfast in the '70s and '80s there was a guy that used to keep lions in his back garden. Again, I'm not kidding. He lived in an ordinary Belfast terraced house. I can't remember his name but he was quite famous for it.

Not sure what I'd call the panther. There are obvious pussy jokes I guess. But imagine taking that for a walk!! Diamante collar and leash. Oh so cool.

But following what RedSarah was saying, ferrets are supposed to be excellent pets, but are full of mischief and hoard things. Me, my sister and Missy saw a woman walking one in Crouch End. She looked embarrassed and irritated in equal measures which just made it funnier. The way they move is hilarious.