Do you know when knock-knock jokes appeared? Let me enlighten you with some quotes from the NPR article “The Secret History Of Knock-Knock Jokes.”

“Writing in the Oakland Tribune, Merely McEvoy recalled that around 1900, a jokester would walk up to someone and pop a question like: “Do you know Arthur?” And the unsuspecting listener would reply, “Arthur who?” And the jokester would say “Arthurmometer!” and run off laughing.”

“The Harrisburg Telegraph of June 17, 1936, credited the rise of Knock-Knock Mania to the selection of Col. Frank Knox as the running mate for that year’s Republican presidential candidate, Alf Landon. People at WKBO radio station in Harrisburg told Knox jokes on air throughout the day.”

“Knock-knock clubs formed in towns in Illinois, Iowa and Kansas… The Knock-Knock Song by Vincent Lopez, et al., became a favorite of some big bands.”

“By September of 1936, spoilsports were ready for the knock-knock fad to fade away. “The best knock-knock was made by me,” observed Heywood Hale Broun in his column, which appeared in the Reading Times. “It goes: ‘Knock-knock. Who’s there? A gang of vigilantes armed with machine guns, leather straps and brass knuckles to thump the breath out of anybody who persists in playing this blame fool knock-knock game.’ “”

“Writing near the end of 1936, D.A. Laird — director of the Rivercrest Psychological Laboratory at Colgate University — threw cold water on the knock-knock fever in America. He delivered a lengthy screed against mass manias of many types — including knock-knock jokes. Laird spoke of people who incessantly pun and of those who enjoyed the jokes as if they were sick.”

So it seems that knock-knock jokes had quite a brief heyday, though of course they remain popular among children to this day.

And now we have to end with my favourite knock-knock joke:

Knock, knock.
Who’s there?
The interrupting cow.
The interrupt —
Moo!