Ji Seung-ryeol, 41, prides himself on his sense of fashion.

He diligently shares mirror selfies on Instagram, where everyone knows the more likes you get, the cooler you are.

So he was bewildered to find out that men his age have become the subject of ridicule online, mocked for shoehorning their way into styles associated with Gen Z and younger millennials.

AI-generated caricatures of this demographic have gone viral on social media: a middle-aged man decked out in street wear and clutching an iPhone. The kids call them “Young 40s”.

The memes have made Ji’s beloved Nike Air Jordans and Stüssy T-shirts the butt of jokes—and the source of much indignation.

“I’m just buying and wearing things I’ve liked for a long time, now that I can afford them,” he tells the BBC. “Why is this something to be attacked for?”

Once celebrated as pioneers of taste in the 1990s, the tide of public opinion on 40-year-olds turned after the release of the iPhone 17 last September.

The smartphone, long considered the preserve of the youth, was suddenly recast as a tacky trademark of Young 40s. These are, in the words of Gen Z Jeong Ju-eun, people “trying too hard to look young”, who “refuse to accept that time has passed”.

The figures seem to reflect this shift. While the majority of young South Koreans still prefer the iPhone to the Samsung Galaxy, over the past year Apple’s market share fell by 4% among Gen Z consumers and rose 12% for people in their 40s, according to research by Gallup.

Something similar played out a few years back with Geriatric Millennials, born in the early ’80s, whose brand of humour—the crying-laughing emoji, finger moustaches and the word “adulting”—was derided as cringey.

Back then, debate over Geriatric Millennials sparked self-deprecating jokes, think pieces and quizzes dictating if you’re meant to pile on the ribbing or be subjected to it.

The same trends have taken hold in South Korea with Young 40s.

In Korea, age difference, even by a year, forms the basis of social hierarchy. Age is one of the first things strangers ask each other, setting the tone for future interactions: how they address one another, who gets to open the bottle of soju at parties (it’s usually the oldest person) and which way to tip your shot glass (the correct answer: away from your seniors).

But the Young 40 memes also represent Korean youth’s growing scepticism of this almost forced reverence for elders.

Just a few years ago, the term “kkondae” was another buzzword among young South Korean to describe an annoying breed of rigid, condescending elders.

Such friction has been exacerbated by social media, where “multiple generations mix within the same space”, says Lee Jae-in, a sociology professor at Korea University’s Sejong campus.

“The old pattern where different generations consumed separate cultural spaces has largely disappeared,” he adds.

Popularised in marketing circles in the 2010s, the term “Young 40” originally referred to consumers with youthful sensibilities. They were health-conscious, active and comfortable with technology—an important target demographic for companies.

“In the past, people in their 40s were seen as already old,” says Kim Yong-Sup, a trend analyst widely credited with coining the term “Young 40”.

As the median age of South Korea’s society rose, however, these people were “no longer on the verge of old age but at the centre of society”, he says.

But the marketing term has since taken a viral, sardonic turn. Over the past year, “Young 40” was mentioned online more than 100,000 times – more than half the references were used in a negative context, according to analytics platform SomeTrend. Many of them appeared alongside words like “old” and “disgusting”.

An offshoot of the meme is Sweet Young 40, a sarcastic label for middle-aged men who like to hit on young women.

Some see the jokes about Young 40s as a form of punching up: these are people at the peak of their careers, who amassed wealth in a time of economic stability and a property boom.

On the other side are Gen Z and young millennials, born a couple of decades later, who face soaring house prices and cut-throat competition in the job market. In their eyes, Young 40s represent “the generation that made it through just before the door of opportunity closed”, according to psychologist Oh Eun-kyung.

“They are seen not simply as individuals with personal tastes, but as symbols of privilege and power,” she says. “That’s why the energy of mockery is focused on them.”

But Ji, the 41-year-old fashion enthusiast who lived through the so-called golden era, tells a different version of that story.

After experiencing the Asian financial crisis as a teen, Ji entered a tough job market in his 20s, submitting around 60-70 applications to land a job. His generation is one that “had very little to enjoy growing up, and only began to enjoy things later, as adults”, he says.

Now at the workplace, he often finds himself sandwiched between two worlds. The generation above him ran a “strict, top-down system where you did what you were told”, while below him is “a generation that asks ‘why””.

“We’re a generation that has experienced both cultures. We feel caught in between.”

While the ability to straddle two generations was once a badge of honour, Ji says he has become self-conscious about interacting with younger colleagues for fear of being labelled a kkondae or Young 40.

“These days, I hardly organise drinking gatherings,” he says. “I try to keep conversations focused on work or career concerns, and only share personal stories when discussions naturally deepen.”

According to Kang, another fashionable 41-year-old, sitting at the heart of the Young 40 meme is a deeply human desire.

“As you get older, longing for youth becomes completely natural. Wanting to look young is something every generation shares.”