The knock-knock joke is a structured word play joke that uses call and response. The joke presents a scenario in which the speaker is pretending to knock on the front door of the listener. The speaker initiates the joke by saying "knock-knock", and the listener responds by saying "who's there". The speaker then says a phrase to identify themselves, and the listener repeats the phrase and asks "who?" to request more information. The speaker then delivers a punch line using word play based on the phrase. The first modern knock-knock jokes were told in the United States in the 1930s, and they became a fad in 1936 with widespread use in the United States and the United Kingdom.
Structure
Knock-knock jokes are a type of word play joke, which derive their humor from the conflation of homonyms. The joke is performed cooperatively by the speaker and the listener in a call and response format as they create a scene depicting a visitor knocking at a door. The joke is dependent on the speaker and the listener having previous exposure to the joke's format and enough general and linguistic knowledge to understand what is being referenced in the punchline.
A standard knock-knock joke has five lines of dialogue. The line is an example of onomatopoeia.
In the second line, the listener's response of "who's there" has them play the role of someone inside their own home as the speaker knocks.
The origin of the knock-knock joke, or the first appearance of the phrase "knock knock, who's there", is sometimes attributed to William Shakespeare for his 1606 play Macbeth. In Act 2, Scene 3, the character of the porter gives a soliloquy about a porter accepting people into hell. He compared it to a joke that emerged in the flapper community around 1920 where a woman would ask "Have you ever heard of Hiawatha?", and upon being asked "Hiawatha who?", she would respond with " a good girl ... till I met you." In the game of Buff, a child with a stick thumps it on the ground, and the dialogue ensues:
Modern knock-knock jokes
The exact origin of knock-knock jokes is uncertain, but true knock-knock jokes had emerged in the United States by the 1930s. Outlets like The Gridley Herald and The Milwaukee Journal also reported on knock-knock jokes that year as a new parlour game and derided it as uninteresting. Meanwhile, a popular knock-knock joke was made at the expense of King Edward VIII.
The Edgmont Cash & Carry, a grocery store in Chester, Pennsylvania, used knock-knock jokes in its advertisements and held a contest for the best knock-knock jokes.
Fred Allen's 30 December 1936 radio broadcast included a humorous wrap-up of the year's least important events, which included a supposed interview with the man who "invented a negative craze" on 1 April: "Ramrod Dank... the first man to coin a Knock Knock."
After peaking in 1936, knock-knock jokes received greater push-back from critics who saw them as unfunny, pseudo-intellectual, or pathological. Despite this, they remained a popularly known joke format.