Bones: It is a human characteristic to love little animals, especially if they're attractive in some way.
Spock: Doctor, I am well aware of human characteristics. I am frequently inundated by them, but I've trained myself to put up with practically anything.
Bones: Spock, I do not know too much about these little Tribbles yet, but there is one thing that I have discovered.
Spock: What is that, Doctor?
Bones: I like them... Better than I like you.