Plenty of North American buildings skip the 13th floor, and plenty of people knock on wood without believing a word of it. Nobody quite follows the rule, nobody quite drops it, and that half-committed state is where most superstitions live.
Korea has its own set, and three of them travel well: a fan that can supposedly kill you in your sleep, a name that must never be written in red, and a soup you must not eat before a big test. They get lumped together on lists, yet they sit at very different distances from daily life.
Whether any of them is true gets one line below. The space goes to where each one stands today, which ones people still keep out of habit, and which ones have turned into running jokes.
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| Three small things that carry big Korean superstitions: a fan, a red pen and a bowl of seaweed soup. |
Where the Line Falls
Beliefs that cost almost nothing to follow tend to last, and beliefs that ask for real effort drift into jokes. GQ Korea's October 2024 piece on superstitions that many people still believe despite science included the closed-room fan, which tells you something about how stubborn the belief is.
Rules on such lists are rarely about conviction. They run on a small itch of discomfort, and the cheaper a habit is to keep, the easier it is to keep scratching that itch.
Think of it as a ladder of effort. At the bottom sit rules that take one second, like picking a different pen. In the middle sit rules that need a small plan, like a different breakfast. At the top sit rules that ask you to be uncomfortable, like sweating through a night with the fan off and the windows shut, and those are the ones that turn into jokes first.
One limit before going further: no survey of how many Koreans follow these three beliefs today turned up in my research. What follows leans on press coverage, expert comments, and the habits that show up in products, schools and etiquette.
Fan Death: The Fan That Learned to Switch Itself Off
Fan death is the belief that sleeping in a closed room with an electric fan running can kill you, and no fan has been shown to do it. Dr. Lee Yoon-song of Seoul National University has compared it to claiming you could suffocate from a television or a radio, and he noted that the people autopsied as supposed victims were mostly elderly, with heart disease or alcoholism.
Scientists have answered the claim repeatedly. Dr. Suh Hee-sun has said that not a single death caused by an electric fan has been reported anywhere in the world, and KAIST professor Rim Chun-taek once sat for two hours in a closed room with a fan running and showed no change in his vital signs. That covers the science, and the culture around the belief is the interesting part.
According to Wikipedia's summary, the earliest documented reference ran on July 31, 1927, in a Korean newspaper, claiming that spinning blades create a vacuum and starve the sleeper of oxygen. A popular theory says the government invented the idea during the 1970s energy crisis to cut household electricity use, but Slate disputes that, since the 1927 article predates the crisis by decades.
Officialdom did lend the belief some weight. In 2006 the Korea Consumer Protection Board listed asphyxiation from fans among the five most common summer accidents, citing 20 alleged cases from 2003 to 2005, and recommended timers and open doors. An official alert like that gave the story a stamp of authority it had never earned, and the belief outlived the press release.
These days the belief is honored mostly through hardware. Korean fans typically come with a built-in timer, and the standard advice is to use it, crack a door and avoid aiming the airflow at your face all night. One PRI writer's mother kept the rule alive in her house with a single sentence: "What if my kid dies?"
A 1997 Korea Herald article claimed at least 10 deaths, which shows the belief once got serious print in English too. Korean news outlets still report alleged cases now and then, often adding that no evidence ties the fan to the death. Foreign visitors tend to meet the whole thing with open amusement. Dry skin, a stiff neck and irritated airways are the real complaints a fan blowing on you all night can cause, and a timer handles those too.
Red Ink: A Living Name Belongs in Black
Writing a living person's name in red is taboo in Korea, and the reason is red's link to death. For many readers it works the way black does at a Western funeral: the color itself carries the message.
A Gwangju News explainer ties the habit to funeral practice. When someone dies, the name is recorded in red in the family register and on funeral banners. Putting a living person's name in the same color borrows that role, which is why the gesture stings.
The rule has a precise boundary, and that precision is part of why it still works as etiquette. Red stamps and seals on official documents are fine. The taboo lives in handwriting, and the target is a name in particular.
GQ Korea describes the belief as having come from China, though pinning down an exact origin is difficult. A Romanian expatriate quoted in a Wikitree column said she was startled to learn the rule at all, which shows how invisible it stays until someone breaks it.
Of the three beliefs, this one asks the least of anybody. You swap a pen and the problem vanishes, and that cheapness helps explain why it has outlasted a rule that asks you to sweat through a summer night.
Seaweed Soup: Birthday Food, Exam Day Villain
Seaweed soup, miyeokguk (미역국), gets skipped on exam day because its slippery strands suggest slipping up on the test. The wordplay works because the verb for slipping, 미끄러지다, is also what Koreans say about failing an exam.
The irony is that miyeokguk is the traditional birthday soup, so families who serve it all year pull it from one specific morning. AFP drew attention to the habit in its coverage of the November 2025 college entrance exam, which Reuters said more than 500,000 people sat. Oily foods get a similar side-eye on that day, according to a Daum Korea quiz on exam-day taboos.
Western students have their own version. USC folklore records students avoiding seaweed before exams because it is slippery, and plenty of American athletes refuse to wash a lucky jersey during a winning streak. The Korean version gets more attention because a whole country sits the same test on the same day, so one slippery soup becomes a national breakfast decision.
This one is easy to keep because the cost is a single meal. Rice and a different soup fill the gap without much fuss. Families piling on other precautions that morning rarely stop at the seaweed.
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| Many Korean buildings label the fourth floor "F", since the number four sounds like the word for death. |
Jokes, Habits and Everything Between
Sorted by how alive they are, the three fall in different places. Seaweed soup is still a working habit on one morning a year, red ink lives on as etiquette, and fan death sits closest to a joke with a timer attached.
Other beliefs fill in the map. Many Korean buildings label the fourth floor "F" because the number four sounds like the word for death, which is the same logic behind the missing 13th floor in North America. Cutting your nails at night is said to let mice eat the clippings and turn into your double. Giving shoes to a partner means they will walk away, and dreaming about pigs is supposed to bring money.
The last two are mostly play, with a wink built in. Fan death and red ink are different. Neither has a workaround that people find funny, and each still earns a quiet nod of caution from people who would never call themselves superstitious.
A 2014 Chosun University survey of 142 college students, as reported by the JoongAng Daily, found that seven in ten showed what it called "low cognition" of superstitions. The wording is vague and the sample is small, so it points in a direction and settles nothing.
How to Handle Them as a Visitor
The practical rules are short. Leave names out of red pens, even in a casual note. If a Korean host sets a fan beside your bed, expect a timer, and take it as plain hospitality.
If you cook for a friend with a big exam coming, keep the seaweed soup for their birthday, when it is exactly the right dish. Shoes are a risky gift for a partner, though a pair for a friend carries no such baggage.
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| A timer and a cracked window: the modern Korean answer to fan death. |
Ask a Korean friend about any of the three and the answer will probably come with a laugh. Most Koreans who keep these habits will cheerfully admit they do not fully believe in them. The habits hang on anyway, held up by a little discomfort and a cheap workaround, which is a fair description of how superstition works in most places, Korea included.
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