In South Korea, men in their early 40s are being mocked online by Gen Z for trying to dress like younger people. These men, called "Young 40s," wear streetwear brands like Nike Air Jordans and Stüssy and often use iPhones. Social media memes show caricatures of middle-aged men in youthful styles, making these fashion choices a joke among the younger crowd. Ji Seung-ryeol, 41, told the BBC, "I'm just buying and wearing things I've liked for a long time, now that I can afford them. Why is this something to be attacked for?" The trend started after the iPhone 17 release, when young people began seeing the device as a symbol of middle-aged men trying hard to look young. Research shows Apple's iPhone use fell 4% among Gen Z but rose 12% among people in their 40s last year. Similar age-based jokes happened before, like with early '80s-born millennials called "Geriatric Millennials," who were seen as cringe for their old-style internet humor. Age plays a huge role in South Korean society, shaping social respect and interactions. But younger generations now challenge the usual respect for elders, shown through terms like "kkondae," meaning condescending older people. Social media mixes generations, stirring more youth scepticism. Originally, "Young 40" described healthy, tech-savvy consumers in their 40s. But now, over half of online mentions are negative, pairing "Young 40" with words like "old" and "disgusting." Some memes mock middle-aged men who flirt with younger women as "Sweet Young 40." Experts say this mocking reflects deeper tensions. Many Young 40s grew up during tough times and are now in career peaks with some wealth. Gen Z faces high house prices and job competition, seeing the Young 40s as a privileged generation. Psychologist Oh Eun-kyung said, "They are seen not simply as individuals with personal tastes, but as symbols of privilege and power. That's why the energy of mockery is focused on them." Ji shared his experience: he faced a difficult job market and feels stuck between older strict bosses and younger workers who question rules. He tries to avoid being seen as a rigid elder or part of the Young 40 meme by keeping social work talks limited. Fashionable 41-year-old Kang said, "As you get older, longing for youth becomes completely natural. Wanting to look young is something every generation shares." The Young 40 meme shows how each generation struggles with growing older in a fast-changing world.