Quote from Phoebe in The One with the Lottery
Rachel: I'm hoping that if she hears it enough, it'll be her first word. Ross: Although if we're gonna do that, we should probably call me "Daddy" too. Phoebe: Ooh. I like that, Daddy. Ross: I was just talking about Rachel. Phoebe: Is Daddy getting angry? Is Daddy gonna spank me? Ross: Well, that depends. Have you been a bad? No, I can't.