We've all been there. Maybe it was a job interview, maybe it was a first date. Maybe it was just a particularly long car journey with a bunch of relatives you really didn't want to offend. Whatever the situation though, I'm pretty sure we can all relate to the *truly agonising* experience of having to hold in a fart.
As it turns out, though, holding in a stinky whisper can be just as bad as letting one rip. In fact, it might even be worse.
According to Professor Clare Collins, a nutrition and dietetics expert at the University of Newcastle, holding in gas can actually cause the fart to come out of your mouth instead.
"Trying to hold it in leads to a build up of pressure and major discomfort," she writes. "A build up of intestinal gas can trigger abdominal distension, with some gas reabsorbed into the circulation and exhaled in your breath. Holding on too long means the build up of intestinal gas will eventually escape via an uncontrollable fart."
She refers to a study which found that "The majority of gases [produced in the gut] are eliminated via flatus [farting] or absorbed into systemic circulation and expelled from the lungs."
Basically: a lot of what doesn't come out of your butt ends up travelling back around your body, into your lungs, and out of your mouth. Pretty gross, right?
What's more, Collins says, is that there's a chance holding in farts could actually cause someone to develop a painful health condition.
"The research is not clear on whether the rise in pressure in your rectum increases your chance of developing a condition called diverticulitis, where small pouches develop in the gut lining and become inflamed – or whether it doesn’t matter at all."
What this research tells us, essentially, is that we should let one go when we feel the urge to. And, annoyingly, there aren't really many ways of reducing how many farts we do in a day.
"Gas in the intestines comes from different sources. It can be from swallowing air. Or from carbon dioxide produced when stomach acid mixes with bicarbonate in the small intestine. Or gasses can be produced by bacteria that are located in the large intestine," Collins explains.
"While these gases are thought to perform specific tasks that impact on health, producing excessive intestinal gas can cause bloating, pain, borborygmus (which means rumbling sounds), belching and lots of farts."
But there are certain foods that will make your releases particularly pungent.
"The smelliest farts are due to sulphur containing gases," she said. "This was confirmed in a study of 16 healthy adults who were fed pinto beans and lactulose, a non-absorbable carbohydrate that gets fermented in the colon. The odour intensity of flatus samples was evaluated by two judges (pity them)."
It was concluded, however, that charcoal-lined underwear can absorb a lot of the smell.
So, next time you're out with your significant other, or trapped in a lift with your work colleagues, you'd best hope you haven't consumed too much dairy (or that you're wearing your special undies) - because that fart is going to find its way out of you one way or another.