Whoa, What was that again?

Here is my new favorite line from an old television show, "The Beverly Hillbillies".
In this episode, Jethro is in a psychiatrist office, although he thinks that he is in an MD's office. The psychiatrist is asking him questions about his family members and then says " Do you have any brothers?',to which Jethro replies, " No, sir, but I have a sister who has one."