10x16 "The One with Rachel's Going Away Party"

As Erica arrives in New York to prepare for the baby's birth, the gang hold Rachel's going away party, during which gives each of her friends an individual goodbye moving them all to tears, except Ross leaving him hurt and wondering why she doesn't say goodbye to him. Rachel later reveals to Ross that with their history, it would be too hard for her to say goodbye to him and the emotional argument leads to them sleeping together. Monica and Chandler start packing up their apartment and Chandler finds a pair of handcuffs and tries to find out who they belong to. Erica goes into labor, leading Chandler and Monica to rush her to the hospital.