Quote from Phoebe in The One with the Breast Milk
Joey: Monica, what are you doing? You can't go shopping with her. What about Rachel? Monica: This is going to be a problem, isn't it? Chandler: I mean, come on. You're going to Bloomingdale's with Julie. It's like cheating on Rachel in her house of worship. Monica: But I- Phoebe: Monica, she will kill you. She will kill you like a dog in the street!