Learn English – the origin of the knock-knock joke

etymologyjokes

Almost everyone knows about knock-knock jokes. Who made them up, and why did they catch on?

Best Answer

Some claim they originated in the Middle Ages as a call-and-answer password format. Others, as @Callithumpian notes, cite passages in Shakespeare.

Here is a legitimate reference to their existence in America in 1936:

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This is the first legitimate printed reference I can find.