Do you have a scrotal tongue? The answer may surprise you.

Before you start insisting your tongue doesn't have testicles, know this: Scrotal tongues are super-common, occurring in around 5% of the U.S. population, according to the American Academy of Oral Medicine.

So what in the world is a scrotal tongue, if not a scrotum growing in your mouth?

Scrotal tongue is simply when the top surface of your tongue develops cracks or grooves — like this or this. The condition is also known as fissured tongue, grooved tongue, furrowed tongue or plicated tongue. The cracks can be shallow or deep, single or multiple, and often include a deeper crevasse down the center of the tongue, according to the AAOM.

A 1906 illustration of scrotal tongue Wikimedia Commons

Why does scrotal tongue occur? There seem to be a bunch of reasons — some more legitimate than others.

The AAOM says the cause of scrotal tongue "is not known," and that some authorities believe it's just "a variation of normal." According to Colgate's Oral Care Center, "people usually are born with" the condition.

It all seemed believable — until I remembered You Are What You Eat, a BBC nutrition show I watched all the time as a kid, because Canada didn't have Nickelodeon. On the terrible-but-addictive show, health guru Gillian McKeith traveled around Britain shaming people for their weight and for eating fatty foods.

Part of McKeith's shtick — besides analyzing people's poop — was detecting health problems by looking at their tongues. The technique "has played an indispensable role in the practice of Ayurveda and Traditional Chinese Medicine," according to McKeith's site.

The tongue is "like a window to your insides, with each area of the tongue correlating to a different organ," McKeith writes in Living Food for Health. She describes a patient, Edna, who had "deep scalloped edges around the sides of her tongue, similar to teeth marks. This is a give-away for a sluggish spleen. And she had a midline tongue crack, indicating a weak digestion."

Is tongue diagnosis legit? "To anyone who knows the slightest bit about science, this woman is a bad joke," the Guardian wrote of McKeith in 2007.

Whether or not it's relevant, I should also note that McKeith is very mean. "You eat like an unhealthy slob man," she once yelled at a woman on her show. "How many croissants do you eat in a day?!"

But back to scrotal tongues.

Wikimedia Commons

It turns out, a scrotal tongue can point to nutrition problems. Research has proven it. In a 1987 study published in the British Journal of Oral and Maxillofacial Surgery, scientists examined blood samples from 40 people with fissured tongues. Compared to a non-scrotal-tongued control group, the test subjects had "slightly lower" mean levels of vitamin B12, ferritin and folate.

The findings still seem to hold up. "Bad breath, a bright red tongue that may have fissures, loss of taste, dry mouth, numbness and bleeding are signs that you need more vitamin B12, which you can find in poultry, fish, shellfish, meats, milk and eggs," dentist Jonathan B. Levine wrote in a DoctorOz.com blog post about "detecting nutritional deficiencies at the dentist."

A scrotal tongue can also point to low levels of vitamin A, according to the National Organization for Rare Disorders.

It's also been linked to health conditions such as Down syndrome and Melkersson-Rosenthal syndrome, according to NORD.

Wikimedia Commons

Finally, I had to know: Why, in the name of all things holy, is it called "scrotal tongue"? This question's harder to answer. Merriam-Webster has no tongue-related definition of "scrotal."

The word "scrotum" may come from the Latin word "scrautum" — a "leather quiver for arrows," according to Dictionary.com. Interesting, sure, but also not tongue-related.

At a loss, I re-read Colgate's description of scrotal tongue and came across the following sentence: "It makes the tongue look wrinkled."

Wrinkled... like... a scrotum?

I can't be completely certain, but "scrotal tongue" might be so named because the cracks and grooves make your tongue look like a wrinkly ol' ballsack. Enjoy the rest of your day!