We’ve all been there. You’re out running errands, walking around Home Depot or Target, when it hits.

You gotta go.

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Turns out, there’s actually a scientific reason why shopping makes you have to poop. It was brought to the forefront recently by an Australian TikTok user who posted from Bunnings, a hardware chain down under.

“Somebody tell me why when I take one step into Bunnings, I need to go to the toilet?” he pondered.

American commenters commiserated, sharing similar experiences from Lowe’s or TJ Maxx.

There’s even a name for it: the “Mariko Aoki” phenomenon, coined for a Japanese author who shared a short story about the seemingly-ubiquitous feeling in 1985.

So, why does it happen?

There’s no definitive answer, but fellow Aussie Dr. Zac Turner offers some theories.

“The enteric nervous system (ENS), often called the ‘second brain’, governs digestive processes and chats constantly with the brain via the vagus nerve,” he recently explained to news.com.au. “This gut-brain banter can lead to surprising outcomes, including sudden bowel movements triggered by sensory or psychological cues.”

Almost anything can provoke your gut to start moving: smells, lighting, stress, etc. And all of those triggers are turned up a notch when you’re shopping.

“Bunnings is a sensory playground: timber, fertilizers, potting mix, and varnishes mingle with the unmistakable aroma of sausages sizzling outside,” Turner said. “These smells can stimulate the vagus nerve, kicking digestion into gear and creating that all-too-familiar urgency.”

The ‘Mariko Aoki Phenomenon’ is named for the Japanese author who wrote about the all-too-common feeling

“It’s also a place where new projects come to life, containing a maze of choices and decisions. Whether it’s excitement or low-level stress, the gut-brain connection might respond with an urgent ‘time-out’ request,” he added.

Physical activity can also stimulate your bowels. Needless to say, there can be plenty of that at a hardware store—which can lead to the intense need to poop.

On the other hand, a calmer, more mellow shopping experience like a bookstore can also set you off.

“There could also be psychological conditioning at play if someone associates these spaces with relaxation or comfort,” said gastroenterologist, Dr. Kyle Staller.