On the January 11 1966 episode of NBC sitcom Please Don't Eat the Daisies (inspired by the Doris Day/David Niven feature film), the kids suspect their father is a secret agent. This is reaffirmed when he has a chance encounter with Man From U.N.C.L.E. star David McCallum, in an early example of cross-promotion of two popular TV shows. The surprise ending has dad calling in someone to convince his boys that he is not a spy. To the surprise of no one, that person turns out to be McCallum's fellow U.N.C.L.E. star Robert Vaughn, seen here in a publicity photo. The show had the desired effect at the time, with kids enthusiastically talking about the cameos the next day. The only question we have is: where are those sweatshirts today? They would be worth a fortune on eBay!
(Thanks to reader Bill Parisho for the photo)