Season 8: Episode 183: The One With The Secret Closet
When a concerned Joey takes Rachel to the hospital because of pain relating to her pregnancy, he realizes that his intense romantic feelings for her are excluding Ross from the joys of impending fatherhood. Joey reluctantly makes a gallant suggestion that could change all of the friends' lives. Meanwhile, Chandler becomes obsessed with finding out what is behind the locked door of Monica's forbidden, secret closet. And Monica agrees to let Phoebe massage her--but Phoebe regrets doing so when Monica ecstatically responds with suggestive grunts and groans.