Quote from Phoebe in The One in Vegas (Part 1)
Rachel: That'll be nice, actually, to have the apartment to myself for a night. Phoebe: Oh, yeah, so you can walk around naked. Rachel: No, so I can be by myself. You know, have a little alone time. Phoebe: Naked alone time. Rachel: No, Phoebe. Just because I'm alone doesn't mean I wanna walk around naked. I mean, you live alone, you don't walk around naked. Phoebe: Uh-huh. Why do you think it takes me so long to answer the door?