Google: Why does my cat lick me?
John Green: Okay, I'm gonna let you in on a little secret
John Green: Cat's believe that all other organisms are cats.
John Green: Once you realize that, a lot of cat behaviour begins to make sense.
John Green: So, why does your cat lick you?
John Green: Because it thinks it's grooming you.
John Green: So, when your cat licks you, he's thinking--"I love you, gigantic, hairless cat. And to show you, I will lick you."