This year it became “OK” to be ageist. It became acceptable to digitally flick off your elders or young’uns on social media, to respond “OK boomer” or “OK millennial,” when, in truth, the people being addressed were often far from okay.

It was the year when it wasn’t enough to be precociously talented if you didn’t possess the wisdom of the ages. Billie Eilish, who turned all of 18 last week, admitted to Jimmy Kimmel that she didn’t know who Van Halen is, and was trolled mercilessly on social media. Hey, she admitted it! When do young folks admit not knowing something when they have a Googleapedia in their hand? No, she’s ignorant, even if “Jump” was released almost two decades before her birth.

While many people — though certainly not all — try to be more sensitive about race, orientation and heritage, ageist tropes ran rampant. “Age-based prejudice is the last acceptable form of prejudice,” says New York University’s Michael North, who studies ageism in the workplace. “People are making age-based generalizations and stereotypes that you wouldn’t be able to get away with about race or background. Insert some sort of racial or ethnic group, or ‘OK Woman,’ and it wouldn’t go over too well.”

People are getting away with it. This year, the baby boom was blamed for almost everything: the fate of the planet, Congress, college debt, plastic straws, the ending of “Game of Thrones.” An entire generation was perceived to be operating as a giant monolith, mind-melded in its intention to make young people miserable for the rest of their long lives. Never mind that old people were once young, struggling, loaded with debt, facing a lousy job market, expensive housing, inflation. (Yes, there was something called inflation. It had to be whipped. Ask your parents.)

And, guess what, millennials? You are acquiring property. So, you know, patience.

The sewer of mockery flowed both ways, upstream and down. It was funny, except when it wasn’t. If young folk derided the Olds for leaving an environmental and fiscal mess, the baby boom was happy to sling verbal mud in their direction.

After “OK boomer” erupted, AARP senior vice president and editorial director Myrna Blyth said in an interview with Axios, “Okay, millennials, but we’re the people that actually have the money.” (AARP long stood for American Association of Retired Persons, but now a growing number of older Americans can’t or won’t retire.)

The large field of presidential contenders, ranging from septuagenarians (Bernie Sanders, Elizabeth Warren, Joe Biden, Mike Bloomberg, Donald Trump) to millennials (Pete Buttigieg, Tulsi Gabbard), has launched barbs about age, experience and suitability. Buttigieg — his campaign moniker, “Mayor Pete,” buffing his youth — called for “generational change.”

To many voters, Buttigieg’s rallying cry was about darned time. If Finland can select a 34-year-old leader, why are we stuck with grandparents? To author and anti-ageism activist Ashton Applewhite, “generational change” was a punch. “I see it as actual hate speech,” she says. “We don’t need ‘generational change.’ We need old and young to work together.”

In the most recent debate, Sen. Amy Klobuchar zinged Buttigieg, complete with finger wag, saying he had “mocked the 100 years of experience on the stage.”

Environmental activist Greta Thunberg, 16, was anointed Time’s Person of the Year — “The Power of Youth” declares the cover. Thunberg, in her September United Nations climate summit address, squarely put responsibility on earlier generations: “You are failing us. But the young people are starting to understand your betrayal.” After Time’s selection, some pundits went nuclear over why, among others, Nancy Pelosi, 79, hadn’t been chosen.

Generational conflict has been around since adolescents perfected the eye roll. But children were long instructed to respect age and refrain from talking back, no matter how ludicrous their elders’ behavior. The practice held until the outsized, outspoken and oxygen-sucking baby boom reached adolescence and early adulthood.

More than half a century ago, young people sang of generational disdain (“I hope I die before I get old”) and preached it (“Don’t trust anyone over 30”) until they stopped because the treacherous enemy had become them. In 1969, “ageism” literally became a thing, coined by psychiatrist and gerontologist Robert N. Butler, the first director of the National Institute on Aging.

What distinguishes these latest ageist salvos are their intensity and frequency. It’s an intergenerational quipping contest, fueled by the rapid, reductionist and unrestrictive nature of social media, which makes it far too easy to cast verbal stones. “Social media amplifies previously latent sentiment,” North says.

“My generation grew up having the Internet as a big part of our life,” says Shannon O’Connor, 19, a student at Montclair State University in New Jersey, who was resourceful enough to transform “OK boomer” into an apparel line. “Newer generations aren’t afraid to speak up about what is upsetting them. The Internet is where you dump your frustrations.”

Age groups tend to segregate on distinct platforms, creating echo chambers of consensus. Gen Z and millennials prefer Instagram, YouTube and TikTok — the latter is where “OK boomer” first gained momentum — while their parents and grandparents favor Facebook.

As with any bias, it became common to castigate an entire group for the behavior of an individual. Why target one person — say, Trump or Alexandria Ocasio-Cortez — when you could blame millions? Consequently, the dire state of the planet was pinned on one generation, even lifelong environmentalists, while another was chided for insolence and ignorance.

“These comments may be heartfelt, but there’s very little substance. It obscures the complexity of generational difference,” says Jay Sokolovsky, a cultural anthropologist at the University of South Florida, St. Petersburg. “We need to go beyond the simplistic. It’s a form of blaming a generation for the problems we’re having in society.”

Not everyone agrees. “I think ‘OK boomer’ is funny. Newer generations aren’t afraid to speak up,” says Malick Mercier, 20, a self-described “next-gen storyteller” and Ithaca College sophomore. “Older people tell us we’re always on our phone. I feel like I’m on my voice, talking about things that matter to me.” He says that generalizations can hold true. “If boomers had actually listened to our generation,” Mercier says, “instead of explaining everything to us, I’m not sure ‘OK boomer’ would have happened.”

During her Nov. 5 speech on climate change, 25-year-old New Zealand MP Chlöe Swarbrick responded to heckles from her older colleagues with, “Ok, boomer.” (New Zealand Parliament)

An unprecedented number of generations, as defined by the Pew Research Center, coexist at one time: greatest (born 1927 and earlier), silent (1928-1945), boomers (1946-1964), Gen X (1965-1980), millennials (1981-1996), Gen Z (1997-2012), and To Be Named Later (tykes born after 2012, and good luck plucking a new letter). The baby boom, named for the unprecedented spike in births — 76 million — after World War II, is the only group officially designated by the U.S. Census Bureau.

For centuries, geriatrician Louise Aronson says, civilization was divided into three stages as they related to family, not society: childhood, adulthood and what she deems elderhood, the title of her latest book.

“Human instinct is to categorize people. That part isn’t new,” Aronson says. “What’s new is making it so generational.”

The moment a group is identified and named, people want to assign it characteristics, whether they’re shared or not. The names themselves are often folly. Is the silent generation universally silent? Is the greatest generation, chronicled in Tom Brokaw’s 1998 book on the topic, singularly great?

“It’s not always clear where the names come from and who is making these definitions,” North says. “These groups seem to come about in random waves.” Historically, a generation spanned 20 to 30 years. Counterintuitively, at a time when people are waiting longer to have children, they’ve contracted to 15.

“Age is the only universal social category. Unlike race, gender, socioeconomic status, age has this inevitability, assuming you live long enough,” North says. “It’s this paradox, given that we’re all in this together, that I’m going to be there one day, and we’re making these comments.”

Any day now, boomers won’t be blamed for everything that is not okay. This is the year — can you feel it? — that, according to Pew’s analysis of census projections, millennials are scheduled to surpass the baby boom in sheer size, 73 million to 72 million, because of, well, death. By 2028, Gen X is also projected to be larger than the baby boom, so we’ll probably start blaming them.

In the meantime, perhaps the generations need to be kinder to each other. “Maybe you shouldn’t be degrading us,” O’Connor says. She found an enterprise, selling more than 6,000 pieces of “OK boomer” merch since mid-October, including shirts and sweats that repeat the phrase seven times, punctuated with “Have a terrible day.” Truly, she means no harm.

“It’s a lighthearted joke. We all can be hurt by things,” O’Connor says. “In the end, we’re all human. We’re all the same in the end. We can’t really hold an entire generation to the behavior of a few.” And the “OK boomer” sales help pay her tuition.

Correction: This story initially conflated the greatest generation and silent generation. The greatest generation is actually considered to be the one before the silent generation.