If you take the right (or wrong, depending on your student debt load) university classes, you'll eventually come across the concept of "culture-bound syndromes." They're a fascinating group of psychological and sometimes physical disorders that seem to be caused by the beliefs and practices of specific cultures.
Some of the most interesting examples include "koro" and other related conditions, in which people in certain cultures become convinced that their dicks are retracting into their bodies, and anorexia nervosa, which may seem universal to us but isn't really a thing in cultures that aren't exposed to Western values. And apparently, between 10–25-ish% of Japanese people feel the immediate urge to shit upon walking into a bookstore.
While people in the Western world may also be getting a twinge in their buttholes whenever they walk into a bookstore and just aren't talking about it for obvious reasons, the Mariko Aoki phenomenon, as it's officially called, appears to be pretty exclusive to Japan. Although written reference to the phenomenon dates back to the '50s, it was named after the brave woman who was among the first to publicly ask "Does anyone else get a rumble in the bumble whenever they're near an artfully arranged bookshelf, or is it just me?" in an '80s magazine. It became a media sensation after scores of her fellow citizens felt a rush of relief that someone finally understood them and their colons.
The phenomenon has since been hilariously extensively studied, and people have developed a number of theories about why it happens. Authorities of various credibility have suggested: that the ink and paper used in books (which, hey, could be different in Japan, but no one in the Japanese publishing industry has returned our increasingly desperate phone calls) might have a laxative effect in large doses, the practice of reading on the toilet has created a sort of "Pavlov's ass" situation, or the crouching and squatting that book browsing requires sends a false alarm to the ol' guardians at the gates. Little of that explains why it doesn't happen in other parts of the world, though, so it seems possible that it was just this handful of folks who ate some prunes before a trip to the library and then convinced themselves -- and everyone else -- that it was a thing. Like when someone yawns and then you need to yawn, too, but in your butt.
Top image: Unsplash/Fallon Michael