Quote from Chandler in The One with the Morning After
Joey: Now, we just have to make sure she doesn't find out some other way. Did you think about the trail? Ross: What trail? Joey: The trail from the woman you did it with to the woman you hope never finds out you did it. You always have to think about the trail! Ross: I don't think there's any trail. Chandler: Okay, okay, okay. Chloe works with that guy, lsaac. Isaac's sister is Jasmine, and Jasmine works at the massage place with Phoebe, and Phoebe's friends with Rachel, and that's the trail. I did it.