On "Captain Kangaroo," when Mr. Moose told the Captain (Bob Keeshan) a knock knock joke, what dropped from the ceiling when he reached the punch line?

On the children's TV show, "Captain Kangaroo" when Mr. Moose asks the Captain a knock-knock joke the dropping of balls would come along with the punchline, usually they were 'ping pong' balls. Mr. Moose liked to regularly confront the Captain (Bob Keeshan) with knock-knock jokes and have ping-pong balls fall down from the ceiling where they would hit the Captain on the head. This was a long-running gag.

"Captain Kangaroo" was an American children's TV series that aired in the morning weekdays on the CBS network. The show ran for nearly 30 years, from October 1955, until December 8, 1984. It was the longest-running and best received nationally broadcasted children's television program of its day.

Most episodes could take place in and around the Treasure House or the Captain's Place. There the Captain would interact with puppets, guests, or other members of the cast. This show itself did not have a strict format. One never knew exactly what would happen from one episode to the next. The non format helped to make this show very enjoyable. Also, parents liked this show because at the end of each show the Captain always encouraged them to spend some quality time with their children. He often demonstrated various creative ways that this could be done.

"Captain Kangaroo" was in the end able to win Emmy Awards three times as Outstanding Children's entertainment series (1978–1979, 1982–1983, and 1983–1984).