Corny jokes and bad puns are a calling card of many people, even if their sense of humor induces more groans than laughs. But by and large, those who employ such repartees can, if they so choose (and as we all know, they rarely do), refrain from doing so.

But there are some out there who cannot control themselves. Discussions of livestock result in udder failure. Conversations about geometry always end up going on some sort of tangent. Trips to the bakery are a piece of cake — but camping trips are in tents. These people insist that North Korea is evil (it doesn’t have a Seoul), wonder why Ireland is so small (as its capital is always Dublin), and if you’re Russian, argue that you best move quickly and not be Stalin.

For these people, puns aren’t just a character trait — they’re a neurological disease called Witzelsucht.

Witzelsucht, as summarized by a team of Taiwanese researchers in a paper published in 2005 (pdf here), is marked by “a tendency to tell inappropriate and poor jokes.” Wikipedia, citing another study, notes that a Witzelsucht patient has an “uncontrollable tendency to pun,” finding the jokes “intensely amusing.” These tendencies are caused by an injury to the person’s brain, specifically in his or her right frontal lobe, often caused by stroke. One neurologist, who told MSNBC that he sees several Witzelsucht-afflicted patients each year, described a particularly “dramatic” case: “[He] appeared to be attracted to my reflex hammer. After I checked his deep tendon reflexes and put my hammer down, he picked up the hammer and started to check my reflexes, while giggling.” The humor, of course, was lost on the doctor — and would be to any outside observer as well.

The Taiwanese study speaks of a 56-year-old stroke victim who punned uncontrollably — using a lot of “witticisms and quips,” as the paper describes. The sheer volume of the jokes also interfered with patient’s physicians’ ability to examine him; as the study notes, the man “was euphoric, outspoken, prankish, and was so talkative that an interruption was usually needed to pull the conversation back to the topic or to complete a test.” But like many with the condition, the man was not responsive to the jokes of others.

Unfortunately, there is no cure for Witzelsucht. Io9 notes that some behavioral therapies may be able to blunt the punning, and various medicines may help calm the afflicted down, but in the end, the allure of another pun will certainly prevail.

Bonus fact : In 1987, the world was introduced to the first book in the Where’s Waldo? (originally Where’s Wally? in the UK) series. The book features Waldo, clad in a red-and-white striped cap and shirt, hiding in a scene; the reader’s goal is to find Waldo among the masses. Why does Waldo wear stripes? Because he doesn’t want to be spotted, of course. (!) This was especially true at some U.S. schools and libraries, which decided to remove the book from their shelves. Apparently, one scene in an early version of the book has a woman lying face down on the beach, topless. According to World.edu, that small part of the scene (seen here), as well as other “inappropriate and seditious hidden imagery,” prompted so many complaints that Where’s Waldo? ended up on the American Library Association’s most challenged books list for the 1990s.

From the Archives: Tanganyika’s Laughing Epidemic and Laughing to Death: Two cases where laughter was the symptom, and no puns were needed.

Related: Where’s Waldo? — the 25th anniversary edition.