Quote from Jack Geller in The One Where No One Proposes
Monica: That's okay, Dad, we can wait until later. Jack Geller: Whoa, whoa, whoa. I don't think so. Aren't you ovulating? Monica: Daddy! Jack Geller: Well, you gotta get at it, princess. When your mother and I were trying to conceive you, whenever she was ovulating, bam, we did it. That's how I got my bad hip. Chandler: That's funny. This conversation's how I got the bullet hole in my head.