Allen Wittman and Andrew Masters are two grown men who make a living selling bathroom humor.

In 2005, the two former engineers founded Liquid Ass Novelties, LLC, in North Carolina. At the time, their entire business was based on selling a spray that comes in a one-ounce plastic bottle bearing the company’s name. It’s exactly what you’d expect: A water-based stench capable of emptying rooms in a matter of minutes.

“It’s like if you stuck your nose up to an asscrack of a plumber who hasn’t showered in three days,” Wittman says.

Wittman invented the spray in his teenage bedroom when he was in high school and tested it out by pouring four ounces into a heat radiator in a foyer bathroom near the gym, where a basketball game was ongoing in the dead of winter. By halftime, the doors to the school were open in an attempt to rid the room of the smell, despite the snowfall.

Decades later, Wittman met Masters in the electrical department in a trucking company based in Illinois. They became friends who shared a love of practical jokes, and one day decided to use Wittman’s remaining stash at an office ice cream social, effectively ruining it.

When the company eventually eliminated their positions, the two decided they could probably make a living out of their stinky product. They figured their target market would be similarly-minded pranksters eager to cause a little smelly mayhem. They were right, and had plenty of success with that audience, but to Wittman and Masters’ surprise, they also managed to reach customers with more noble pursuits.

Researchers, hospitals, and programs designed to train medical professionals routinely order Liquid Ass. The stench so realistically mimics the human colon, it’s the perfect training tool to teach medical responders how to maintain focus and professional demeanor in the midst of a truly overwhelming smell. And because the stench is universally offensive, psychologists have found it’s the perfect tool for studying the effects of disgust on all sorts of human behavior, from political decision-making to health care choices.

Liquid Ass even made its way into military training operations, as Mary Roach describes in her book Grunt. It’s a key ingredient in fake bowels filled with dyed oatmeal, used in a device called a Cut Suit, a creation of a training company called Strategic Operations in San Diego, California which trains some members of the US military. The Cut Suit is a wearable prop that realistically mimics wounds; it starts off looking like healthy skin, and when you cut into it, it looks and smells like a real body would if it were cut open. The suits have been used, for example, by Navy medics practicing attending to wounded soldiers during an ongoing battle.