Knock, knock. Who’s there?
It is the most universally recognized joke format in the English language. Children tell them before they fully understand what a joke is. Adults groan at them. They are a staple of playgrounds, pop culture, and bad icebreakers.
But where did the "knock-knock" joke come from? Its origins are surprisingly murky, involving Shakespeare, Prohibition-era flappers, and a bizarre national fad that swept America in the 1930s.
The Shakespearean Setup
The phrase "knock, knock" used as a comedic device actually dates back to William Shakespeare.
In Macbeth, immediately following the gruesome murder of King Duncan, a heavily intoxicated porter stumbles to the castle gates. To break the intense dramatic tension, Shakespeare gives the porter a comedic monologue where he plays a game with himself:
"Knock, knock, knock! Who's there, i' the name of Beelzebub?"
He proceeds to act as the gatekeeper of hell, imagining different sinners knocking at the door and making jokes about their ultimate fates. While it lacks the pun-based punchline of a modern knock-knock joke, the rhythmic, call-and-response comedic structure was born on the stage of the Globe Theatre in 1606.
The "Do You Know" Precursor (1900s - 1920s)
Before people were knocking, they were asking if you knew someone. In the early 20th century, a popular parlor game and street joke format was the "Do You Know" joke.
The structure was simple: Person A: Do you know Arthur? Person B: Arthur who? Person A: Arthurometer! (Our thermometer!)
These pun-based jokes shared the exact comedic DNA of the knock-knock joke—the setup, the innocent inquiry, and the punny punchline—but they lacked the rhythmic opening.
The 1930s Fad: America Goes Knocking
The modern knock-knock joke as we know it exploded into the public consciousness in 1936. It didn't just become popular; it became an absolute, inescapable national mania.
The exact "patient zero" of the 1936 fad is disputed. Some historians point to a popular radio show host, Wee Willie Robyn, who used the format on air. Others credit a newspaper columnist in Pennsylvania.
Regardless of who started it, by the summer of 1936, the country was obsessed. * Orchestras played a hit song simply titled "Knock, Knock, Who's There?" composed by Vincent Lopez. * Newspapers ran daily knock-knock joke contests. * Advertisers used the format to sell everything from tires to toothpaste. * Businesses put signs in their windows banning the jokes because employees wouldn't stop telling them.
The appeal in the 1930s was likely tied to the Great Depression. The country was exhausted and broke. The knock-knock joke was free, democratic (anyone could invent one), and profoundly silly. It was a brief, linguistic escape from a grim reality.
The Evolution to Children's Humor
By the 1950s, the adult obsession with knock-knock jokes had faded. The format was viewed as passé or annoying by the general public.
However, the jokes found a permanent, resilient home: the playground.
The structure of a knock-knock joke is perfectly suited for children who are just learning the mechanics of humor and language. 1. It is highly structured. The rigid format acts as conversational "training wheels," providing a safe script for a child to follow. 2. It requires participation. It forces the listener to interact ("Who's there?"), giving the child a sense of power and control over the conversation. 3. It relies on basic wordplay. As children learn vocabulary and phonetics, the simple puns of knock-knock jokes help them experiment with language boundaries.
The Enduring Legacy
Today, the knock-knock joke occupies a unique space. It is simultaneously the lowest form of comedy and a vital developmental milestone.
It is the first joke we learn to tell, and usually the first joke we learn to groan at. But from the bloody halls of Macbeth to a 1930s swing sensation to the backseat of every family minivan, the simple knock at the door remains one of the most enduring comedic structures in history.