It's already sparked a thousand memes and think pieces, and now "OK boomer" has officially been recorded in New Zealand's Hansard.

It was used earlier this week by a Green Party MP who'd just been heckled in Parliament while she was speaking about climate change.

Given the sudden ubiquity of the phrase, you don't have to have been born in the postwar years between 1946 and 1964 to feel like you've missed something.

Here's why you're probably seeing the phrase all over the internet.

Haven't seen anyone say it? Try looking at the Facebook comments under pretty much any news story

Chances are, you're about to step into an intergenerational warzone, like this comment thread about the Melbourne Cup:

As far as those using the phrase are concerned, "boomer" refers less to a specifically defined generation and more to older people generally.

In particular, it's a response to what's perceived to be some older people's sense of entitlement, outdated ways of thinking, or condescending attitudes towards younger generations.

The phenomenon kicked off on TikTok

If you're under the age of, say, 20, that's probably the only explanation you're going to need.

But for the rest of you, we might have to introduce you to the potentially baffling world of TikTok before we proceed.

Basically, it's the spiritual successor of Twitter's old video-sharing platform Vine: TikTok users create and watch videos of up to 15 seconds in which they dance, lip-sync or perform sketches.

There are lot of people on there — earlier this year, the app hit 1 billion downloads.

A lot of the "OK boomer" videos involve TikTok users lip syncing to this song (appropriately named "ok boomer"), which was posted online last month and starts with the line "this one goes out to the 65+ crowd on Soundcloud":

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Another favourite involves reacting to a clip of a man saying, "The millennials and Generation Z have the Peter Pan syndrome, they don't ever want to grow up."

These examples will give you a pretty good idea of what it's all about:

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 57 seconds 57 s Compilation of 'OK Boomer' Tik Tok videos

A lot of people found out about it via the New York Times last week

Its headline proclaimed 'OK Boomer' Marks the End of Friendly Generational Relations, with reporter Taylor Lorenz saying the anti-boomer sentiment was being fuelled by "rising inequality, unaffordable college tuition, political polarisation exacerbated by the internet, and the climate crisis".

Since that article was published, there have been a load of think pieces about the phenomenon.

Some have made the argument that young people have the wrong target.

"It's a mistake to blame all boomers for the sins of the most powerful among them," New York Time's Farhad Manjoo wrote.

Bhaskar Sunkara, writing for The Guardian, agreed the problem wasn't boomers, but rather "that investment banker you went to high school with".

One American radio host said boomer was the "n-word of ageism", something the dictionary didn't agree with…

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Meanwhile, Steve Cuozzo, a boomer writing for the New York Post, wrote that the hate was "totally unjustified":

"If they spent more time studying actual history, which can't easily be found on iPhones, they'd know that boomers were, and remain, the most socially and environmentally conscious generation America ever has ever known."

But another, The Los Angeles Times' Mary McNamara, said she was on the side of the young people using the phrase:

"'OK, boomer' isn't about history or culture; it's just the latest iteration of 'OK, grandpa'. Which stings, of course it does, but guess what? This is exactly how it's supposed to work. Social progression is fuelled in large part by generational tension."

On Twitter, people on both sides of the generational divide just poked fun at each other:

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It's reached the point where this week, the phrase was used in NZ Parliament

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 17 seconds 17 s Chloe Swarbrick responds to heckle with "OK boomer"

Chloe Swarbrick, a 25-year-old Green Party MP, had just made this remark while talking in support of the Ardern Government's Zero Carbon Bill on Tuesday:

"In the year 2050, I will be 56 years old. Yet, right now, the average age of this 52nd Parliament is 49 years old."

She was then heckled by another MP — according to Hansard, they said "that's impossible" — which is when she dropped the "OK boomer" line and kept going.

Unfortunately, we have no advice for what to do if someone says 'OK boomer' to you

No matter how you respond, the fact is, you're probably heading for another "OK boomer":