"How much did Father Christmas's sled cost? Zero, it was on the house."
This joke is met by moans that resonate through a storage facility in London.
This describes a humor-evaluation meeting with a firm that makes supplies for social events. Its repertoire features festive crackers.
The company's founder grins, almost sheepishly at the joke. But the pun has made the cut and will feature in future crackers.
"You measure the joke by the volume of moans and the intensity of the groans around the table," she says.
The secret to a great holiday cracker pun is not the same as a stand-up joke per se. It is entirely about the setting - in this instance, the shared laughter of the holiday dinner table with grandparents, kids and possibly neighbours.
"The goal is for the gag to be a thing that brings the child together with the 80-year-old," she states.
Gathering to experience shared laughter is not only ancient, scientists say, it is probably to be pre-human.
"So when you are laughing with others at the Christmas dinner you are engaging in what's almost certainly a really primordial mammal play vocalisation," says a professor.
Communal laughter, she explains, aids in make and maintain social connections between people.
Researchers have discovered that a lack of these interactions can seriously harm both psychological and bodily health.
"Those you converse with, and laugh with, it results in increased amounts of 'happy chemical' release," the professor adds.
These natural chemicals are the brain's "happy chemicals" and are released both to alleviate tension and discomfort and in reaction to pleasurable experiences, such as laughing with friends over a particularly terrible Christmas cracker joke.
"You're not just laughing at a silly joke with a Christmas cracker," the expert states. "You are in fact performing a lot of the truly important task of making, maintaining the social bonds you have with those you care about."
But what is actually happening within the brain when we hear a joke?
An awful lot occurs in response to humour, it turns out.
Using functional magnetic resonance imaging (fMRI), a type of neural imager which indicates which parts of the brain are more active, scientists have been able to map the regions that receive more blood.
Testing involves imaging the minds of healthy participants and then subjecting them to a database of humorous words, paired with either a neutral sound, or pre-recorded laughter.
"During the study we observed a very interesting pattern of activation," says the professor.
A gag activates not just the areas of the brain in charge of hearing and understanding language, but also neural regions associated with both planning and initiating motion and those linked to vision and recall.
Combine these elements as a whole, and individuals hearing a pun have a complex set of neural responses that support the amusement we hear.
Researchers discovered that when a funny word is combined with laughter there is a greater reaction in the mind than the same phrase when followed by a non-emotional sound.
"This activation occurred in parts of the brain that you would employ to contort your expression into a grin or a chuckle," she explains.
It means we are not just reacting to funny jokes, they are reacting to the amusement that accompanies them.
Amusement, says the professor, can be infectious.
So what does this mean for the chuckles heard around a Christmas table?
"You laugh more when you are familiar with others," she says, "and you laugh further when you like them or care for them."
When it comes to festive cracker jokes, she explains, the positive factor is more likely to be triggered not by the joke in itself, but from the reaction to it.
"The laughter is key. The gag is the terrible holiday cracker joke, and it's just a reason to chuckle together."
Will we ever find the ultimate gag?
Probably not, but that has not stopped researchers from trying to.
Years ago, a professor established a scientific project for the planet's most humorous gag.
Over tens of thousands of gags submitted, with ratings provided by 350,000 people around the world, he has a clearer understanding than most as to what succeeds and what fails.
The perfect festive cracker pun needs to be brief, he explains.
"But they also need to be poor jokes, jokes that cause us to moan," he continues.
The more "awful" the joke, he states the more effective.
"This is because if nobody laughs – it's the joke's shortcoming, not your own.
"What's interesting about the Christmas cracker puns is that not one person find them humorous.
"That's a common experience around the table and I believe it's lovely."
Elara is a passionate writer and photographer who shares insights on creativity and mindful living through engaging storytelling.
