🔗 Share this article

"How much did Santa's sled cost? Nothing, it was on the house."

This one-liner is met by moans that resonate through a warehouse in London.

We're at a joke-testing session with a company that makes supplies for social events. Its repertoire features festive crackers.

The firm's founder smiles, almost sheepishly at the joke. But the pun has made the cut and will feature in upcoming crackers.

"You measure the gag by the volume of groans and the intensity of the groans at the table," the founder explains.

The key to a good Christmas cracker pun is not the same as a good gag in itself. It is entirely about the context - in this instance, the communal laughter of the Christmas meal with grandparents, children and possibly friends.

"The goal is for the gag to be a thing that brings the child together with the 80-year-old," she adds.

The Neuroscience Behind Shared Amusement

Coming together to enjoy shared laughter is not only nothing new, scientists argue, it is probably to be pre-human.

"Therefore when you are chuckling with others around the holiday dinner you are dropping into what's almost certainly a really ancient mammal play vocalisation," says a neuroscience expert.

Communal laughter, she says, helps forge and strengthen social bonds between individuals.

Researchers have discovered that a absence of such interactions can significantly damage mental and physical well-being.

"Those you talk to, and laugh with, it leads to increased amounts of 'happy chemical' release," the professor adds.

These natural chemicals are the body's "feel-good compounds" and are produced both to reduce stress and pain and in response to enjoyable experiences, such as laughing with friends over a particularly awful Christmas cracker gag.

"It's not simply chuckling at a silly joke with a holiday cracker," she states. "You are actually doing a lot of the really vital task of building, preserving the connections you have with those you care about."

What Happens Inside the Mind?

But what is actually taking place inside the mind when we listen to a gag?

A tremendous amount occurs in reaction to comedy, it turns out.

Using functional magnetic resonance imaging (fMRI), a kind of neural imager which shows which areas of the brain are more active, scientists have been able to chart the areas that get more blood flow.

The research entails scanning the minds of healthy participants and then exposing them to a collection of funny words, accompanied by either a neutral sound, or recorded chuckles.

"During the study we observed a really interesting activation pattern of neural activity," notes the neuroscientist.

A gag activates not just the parts of the mind in charge of auditory processing and understanding speech, but also neural areas associated with both planning and starting motion and those linked to vision and recall.

Put these elements together, and individuals hearing a joke have a complex set of neural responses that underpin the laughter we experience.

The Contagious Power of Chuckles

Scientists found that when a humorous phrase is combined with chuckles there is a greater reaction in the mind than the identical phrase when followed by a neutral sound.

"This activation occurred in areas of the brain that you would use to move your expression into a smile or a chuckle," she explains.

It means we are not just reacting to humorous words, they are reacting to the laughter that follows them.

Laughter, says the professor, can be contagious.

So what does this imply for the laughter heard at a holiday table?

"People laugh more when you know others," she says, "and laughter increases further when you like them or love them."

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

"The laughter is key. The gag is the dreadful holiday cracker pun, and it's just a pretext to chuckle together."

The Search for the Ideal Cracker Joke

Will we ever find the perfect gag?

Likely not, but that has not stopped researchers from trying to.

Years ago, a professor set up a research project for the planet's most humorous gag.

Over 40,000 gags later, with ratings provided by 350,000 participants globally, he has a clearer idea than most as to what works and what fails.

The perfect festive cracker pun needs to be brief, he says.

"They must also need to be bad gags, jokes that make us moan," he adds.

The more "awful" the gag, he says the more effective.

"The reason is that if no-one finds it funny – it's the joke's fault, not your own.

"The fascinating part about the Christmas cracker jokes is that none of us considers them funny.

"That's a shared experience at the gathering and I think it's wonderful."