Knock Knock (1940) -Andy Panda Theatrical Cartoon Series
Andy Panda and his dad are busy in the study reading their respective favorite magazines. They hear a knock-knock, and father opens the door. Nobody’s there.
After this is repeated a number of times, the door is taken off its hinges and set on the floor. The knocks are repeated again and again, and, seeing sawdust on the floor, Andy and his dad realize that the knocks come from the roof.
Father climbs to the roof and sees Woody Woodpecker pecking holes in the roof. Then begins a series of episodes in which Andy Panda and his father try to get rid of Woody (including trying to put salt on his tail). They have no success.
Finally, two keepers from an asylum (also woodpeckers) arrive. Then the keepers themselves begin acting like maniacs as the picture ends.
Watch “Knock Knock” on video at Big Cartoon DataBase