"What was the price did Father Christmas's sled cost? Nothing, it was on the house."
This one-liner is greeted with moans that resonate through a storage facility in London.
We're at a joke-testing meeting with a firm that produces products for gatherings. Its repertoire features Christmas crackers.
The company's founder smiles, almost sheepishly at the gag. But the pun has made the cut and will feature in upcoming crackers.
"You measure the joke by the volume of groans and the loudness of the groans around the table," the founder says.
The key to a great holiday cracker pun is not the identical as a stand-up joke in itself. It is entirely about the context - in this instance, the shared laughter of the Christmas meal with grandparents, children and potentially friends.
"The goal is for the gag to be something that brings the child in harmony with the 80-year-old," she adds.
The Science Of Communal Laughter
Gathering to enjoy communal amusement is not only ancient, scientists argue, it is probably to be pre-human.
"So when you are chuckling with others at the Christmas dinner you are dropping into what's very likely a really ancient mammalian social sound," explains a professor.
Communal laughter, she says, aids in forge and strengthen social connections between people.
Scientists have found that a lack of such social exchanges can significantly damage mental and physical well-being.
"Those you converse with, and laugh with, it results in increased levels of endorphin uptake," she continues.
These natural chemicals are the body's "feel-good compounds" and are produced both to reduce stress and pain and in reaction to pleasurable activities, such as laughing with loved ones over a truly terrible festive cracker gag.
"You're not just chuckling at a foolish pun with a Christmas cracker," she says. "You are in fact performing a lot of the truly important task of building, preserving the social bonds you have with the people you love."
What Happens Inside the Mind?
But what is actually happening inside the mind when we listen to a joke?
A tremendous amount happens in response to comedy, it transpires.
Using brain scanning technology, a kind of neural imager which indicates which parts of the mind are working harder, researchers have been able to map the regions that get more blood flow.
Testing involves scanning the brains of volunteer subjects and then subjecting them to a database of funny phrases, paired with either a non-emotional sound, or pre-recorded laughter.
"In the scanner we observed a really fascinating activation pattern of activation," notes the neuroscientist.
A joke stimulates not just the parts of the mind in charge of auditory processing and understanding speech, but also brain areas associated with both preparation and starting movement and those involved in sight and recall.
Combine all of this together, and people hearing a pun have a sophisticated series of brain responses that underpin the amusement we experience.
The Infectious Nature of Chuckles
Scientists found that when a funny word is combined with chuckles there is a stronger reaction in the brain than the same phrase when accompanied by a neutral sound.
"This was in parts of the brain that you would employ to move your expression into a grin or a laugh," the professor says.
It means people are not just reacting to funny words, they are reacting to the amusement that follows them.
Laughter, says the professor, can be contagious.
So what does this mean for the chuckles found around a Christmas gathering?
"You laugh harder when you know people," she says, "and laughter increases further when you are fond of them or love them."
When it comes to festive cracker jokes, she says, the positive factor is more probable to be caused not by the joke in itself, but from the response to it.
"It's the laughter. The joke is the dreadful holiday cracker joke, and it's just a reason to laugh as a group."
The Search for the Ideal Festive Pun
Is it possible to discover the perfect gag?
Likely not, but that has not prevented researchers from attempting to.
In 2001, a professor established a research search for the world's funniest joke.
Over 40,000 jokes later, with ratings provided by hundreds of thousands of participants around the world, he has a clearer idea than most as to what succeeds and what does not.
The perfect Christmas cracker pun must be short, he says.
"They must also be bad gags, puns that make us groan," he adds.
The increasingly "awful" the joke, he says the more effective.
"The reason is that if nobody laughs – it's the joke's shortcoming, not your own.
"The fascinating part about the holiday cracker jokes is that none of us find them funny.
"That's a common moment at the gathering and I believe it's wonderful."
