This article was written with the very kind help of Clare Jonas:

Clare Jonas

Clare Jonas is a science communicator with a PhD in the psychology of perception.

When she’s not talking about merkins in the name of explaining science, she enjoys attempting to guess the names of other people’s dogs and listening to the music of Four Tet.

You can read more of her work at

Why is the ‘Rule of Three’ funny?

“Humor can be dissected, as a frog can, but the thing dies in the process and the innards are discouraging to any but the purely scientific mind.”

– E.B. White and his wife, Katharine S. White

Rach: My driving instructor was a lovely Chinese man who grew increasingly frustrated with my questions about how exactly a clutch worked.

I couldn’t get my head around the biting point if I couldn’t see what I was biting.

How does the engine work, how does the clutch work, what are we doing here in a car park in Mitcham at 10 o’clock in the morning?

Mr. Yeo placed his head in his hands and sighed quietly.

Since learning how to perform stand up comedy, I’ve been struck with similar confusion about how jokes work. I need to know why something is funny to be able to write and perform it with confidence. 

The frog is dying, but I can’t help myself.

Take the rule of three for example. Every comedy course in the world will tell you that the rule of three is funny.

And it is. There’s no question about that. The age-old mechanism of establish, reinforce, subvert is as tried and tested as ‘See it, Say it, Sorted’ isn’t.

But why are three things funnier than two? Why don’t four things work so well? And above all, why do some third-thing punchlines work better than others?

To help me with this, I consulted Clare Jonas from That Thinking Feeling.

Clare, why is a comedic triple funnier than a double or quadruple?

Clare: Good question! I don’t think anyone’s actually tried to figure out this exact thing with an experiment… so I cobbled together an answer from my psychology knowledge. 

First, let’s tackle the number element. In order to make this kind of joke work, you need to establish a category and then flout or subvert it in some way.

It should be obvious why one item in the list won’t work: you usually can’t establish a clear category from just one thing, and you certainly can’t subvert the category. Because a lot of words have multiple meanings, you need the second item in the list to solidify the category, which means it also shouldn’t be the funny thing.

Here’s an example first item: boxers. This could belong to a number of categories…

Underwear: Boxers, Y-fronts

Sportspeople: Boxers, rowers

Dog breeds: Boxers, spaniels

Words that end in -oxers: Boxers, foxers

So, why not establish the category even more solidly with a third or fourth or fifth item before subverting? Because humans have limited attention spans. We usually use working memory (a sort of temporary store for information) to keep track of things that we need to keep in mind right now. When you’re reading or listening to someone tell a story, a lot of your working memory is taken up with what’s going on in the story – events, characters, how things relate to each other. If I ask you to remember a long list while you’re listening to a story, either you’ll forget the list or you’ll lose track of the story. A two-item list is a balance between the need to establish the category and the need to keep your audience’s attention.

A different use of this kind of three-part list is an age-old rhetorical device called hendiatris, which gave us such classics as friends, Romans, countrymen and reduce, reuse, recycle. We have a powerful cultural expectation that the third item in a list will complete it in an emotionally or aesthetically pleasing way. The subversion of that expectation is funny – but why?

I’ve written before about how humour works, and the honest answer is that there’s no one theory which can explain all of it. In many cases, it’s probably about mild tension being resolved. In something like stand-up comedy, this tension might come from a variety of sources, say the topic is mildly taboo or emotionally difficult, or the narrative is gripping and you don’t know what to expect, or even that you’re worried whether the comedian is going to land the joke. If the tension is resolved, you’re relieved – but add a silly or incongruous subversion to that and you are likely to express relief by laughing.

Let’s talk a bit more about incongruity, because you can’t just whack any old incongruous thing on the end of a list to make a funny. Returning to one of the earlier examples…

Boxers, Y-fronts, briefs -> Congruous, not funny

Boxers, Y-fronts, cathedrals -> Incongruous, not funny

Boxers, Y-fronts, merkin -> Incongruous, funny, BINGO!

I like to think of this as a series of concentric circles. The trick is to find something that’s slightly outside the category you’ve established, but not so far that you can’t see any connection between the first two items and the final one (Only Ross Noble and Eddie Izzard can make this funny – Rach.) Underwear and pubic wigs are reasonably closely related, underwear and large buildings not so much. 

In this case, merkin is also good because it’s slightly rude (another type of subversion, this time about social norms of what we ‘should’ talk about in public) and it’s one of those words that sounds funny even if you don’t know what it means, like spatula.

Clare Jonas concentric cirles 1

Not every minor subversion is funny, of course. Some minor subversions might be offensive or confusing, in the general sense or in the specific context of what you are saying and who you are saying it to. 

As with all comedy, the key is keeping in mind who you’re talking to. 

Perhaps your audience is entirely comprised of Conservative women over the age of 80. Will they know what a merkin is? If they do know, will they think it’s too rude? 

Perhaps your audience is made up of curators at the Amsterdam Sex Museum. Will they be so used to merkins that they find them boring? Is it not rude enough?

Clare Jonas concentric cirles 2

Rach: So, the category circles might change size, depending on your audience. If your ‘third thing’ is in the central established category circle, it won’t be a surprise, so it won’t be funny – though if you’re lucky you might have made a hendiatris. If it’s in the ‘TOO FAR’ circle, it doesn’t make any sense.

If it’s in the offensive section, it could be funny, but a stand-up audience might be nervous to laugh out loud. It’s certainly not going to get you booked for the Royal Variety Performance.

In conclusion, establish, reinforce, subvert by the correct amount and you have yourself a punchline.

Postscript: Rach eventually overcame her clutch based confusion, and nailed her driving test on the fourth attempt.

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