🔗 Share this article

"How much did Santa's sled cost? Zero, it was on the house."

This one-liner is met by groans that echo through a storage facility in the capital.

We're at a humor-evaluation meeting with a company that makes products for gatherings. Its catalogue includes Christmas crackers.

The firm's owner grins, nearly sheepishly at the gag. But the pun has made the cut and will appear in upcoming crackers.

"You measure the joke by the volume of moans and the loudness of the groans at the table," she says.

The key to a good Christmas cracker pun is not the same as a stand-up gag in itself. It is all about the setting - in this case, the communal amusement of the Christmas dinner table with elders, children and potentially neighbours.

"You want the gag to be something that brings the eight-year-old together with the grandparent," she states.

The Science Behind Shared Amusement

Coming together to enjoy shared amusement is not only ancient, scientists say, it is probably to be older than humanity.

"So when you are laughing with others at the Christmas dinner you are engaging in what's very likely a really ancient mammal social sound," says a professor.

Shared laughter, she explains, aids in make and maintain social bonds between individuals.

Scientists have found that a lack of these social exchanges can seriously harm mental and physical health.

"Those you talk to, and share laughter with, it leads to increased levels of 'happy chemical' release," she continues.

Endorphins are the brain's "happy chemicals" and are released both to reduce tension and discomfort and in reaction to pleasurable experiences, such as laughing with loved ones over a truly awful festive cracker joke.

"It's not simply laughing at a silly joke with a Christmas cracker," the expert says. "You are actually doing a lot of the really important task of making, maintaining the social bonds you have with those you care about."

Which Happens In the Mind?

But what is actually happening within the brain when we hear a gag?

An awful lot occurs in reaction to humour, it transpires.

Using functional magnetic resonance imaging (fMRI), a type of brain scanner which indicates which areas of the brain are working harder, scientists have been able to map the regions that get more blood.

The research involves scanning the brains of healthy subjects and then exposing them to a database of humorous phrases, paired with either a neutral sound, or pre-recorded chuckles.

"In the scanner we got a really fascinating activation pattern of activation," says the neuroscientist.

A joke activates not just the areas of the mind responsible for hearing and interpreting language, but also neural areas involved in both planning and initiating movement and those involved in vision and memory.

Put all of this as a whole, and people listening to a pun have a sophisticated series of neural reactions that support the laughter we experience.

The Infectious Power of Chuckles

Researchers found that when a humorous word is paired with chuckles there is a stronger reaction in the mind than the identical phrase when accompanied by a non-emotional sound.

"This activation occurred in parts of the brain that you would employ to move your face into a smile or a chuckle," she explains.

It means we are not just reacting to funny jokes, they are responding to the laughter that follows them.

Amusement, according to the expert, can be contagious.

So what does this imply for the chuckles heard around a Christmas table?

"People laugh more when you know people," she notes, "and laughter increases further when you are fond of them or love them."

When it comes to Christmas cracker puns, she explains, the feel-good factor is more probable to be caused not by the joke in itself, but from the reaction to it.

"The laughter is key. The joke is the dreadful holiday cracker pun, and it's just a reason to laugh as a group."

The Quest for the Perfect Festive Pun

Is it possible to find the perfect joke?

Likely not, but that has not prevented experts from trying to.

In 2001, a professor set up a scientific search for the planet's funniest gag.

More than tens of thousands of jokes later, with scores provided by 350,000 participants globally, he has a clearer idea than most as to what succeeds and what fails.

The ideal festive cracker joke needs to be short, he explains.

"They must also be poor jokes, puns that make us groan," he adds.

The increasingly "awful" the joke, he states the better.

"This is because if no-one finds it funny – it's the gag's shortcoming, not your own.

"The fascinating part about the holiday cracker jokes is that not one person considers them humorous.

"It creates a common experience around the gathering and I think it's wonderful."