Season 1: Episode 12: The One With The Dozen Lasagnas
Paolo shows up at the massage shop where Phoebe works and he comes on to her while Phoebe gives him a massage. Phoebe doesn't know whether to tell Rachel or not, but after Ross' encouragement (which is extremely self-motivated and self-serving) she tells her. Rachel breaks up with Paolo and announces that she wants nothing to do with men for a long time. Any man -- which obviously includes Ross. Meanwhile, Carol has found out the sex of the baby, but Ross doesn't want to know, despite everyone around him finding out. Rachel ends up slipping the news -- it's a boy.