Quote from Phoebe in The One with the Red Sweater
Phoebe: Pretty big? It's huge. God, this guy doesn't have a clue. He's just walking down the street thinking: "I had sex with Rachel Green. I rock." Then, bam! He's a father, everything's different. Rachel: Well, it's only different if he wants it to be. I mean, I'm not going to ask him for anything. Phoebe: Okay, then he still has this huge decision to make. Now he's walking around thinking: "Do I want to be a dad?" Then, bam! Monica: What was that "bam"? Phoebe: I don't know. He's hit by a bus.