In "The One with Phoebe's Dad," Phoebe Buffay learns her biological father is a pharmacist upstate and not, as she thought, a tree surgeon in Burma.
Rachel: Phoebe, I thought your dad was in prison.
Phoebe: No, that's my stepdad. My real dad's the one that ran out on us before I was born.
Rachel: How have you never been on Oprah?