McCoy: It's a human trait to love little animals, especially if they're attractive in some way.
Spock: Doctor, I am well aware of human traits, I am frequently inundated by them, but I've trained myself to put up with just about anything.
McCoy: Spock, I don't know much about these things, but I do know one thing. I like them...better than I like you!
Spock: Doctor, they do indeed have one redeeming quality.
McCoy: What's that?
Spock: They do not talk too much.