The Dedgradation of the American Dialogue

It's not like Letterman actually knew which daughter was with Mrs. Mouthbreather and Mr. Tater Salad on their trip to New York.

Obviously the writer of said joke didn't do their research. Obviously the joke was intended for Bristol since she is the one getting all of the media attention and she is the one who is a dirty slut masquerading as a supporter of abstinence.