That's a meme: President Obama and gymnast McKayla Maroney struck her "McKayla is not impressed" pose when members of the Olympics team visited the White House in November.

RACHEL MARTIN, HOST:

So, you've all seen it, right? It is the most-watched YouTube video ever - and this week it surpassed one billion views. And just in case you've taken up residence under a large rock of some kind...

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PSY: (Singing) Opa Gangnam style, Gangnam style...

MARTIN: It's Korean pop star PSY's "Gangnam Style," of course. And it didn't take long for the video to mutate on the Web into versions featuring Mitt Romney, Pokemon characters and the Ohio University marching band.

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MARTIN: So, a little Internet 101 for the uninitiated. When these images and ideas take on lives of their own on the Internet, the variations are called memes, and memes have been with us for years. Anyone remember the dramatic chipmunk?

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MARTIN: But this year, it feels like the meme phenomenon has taken off in a new way. Every time you turn around, the random, the obscure, the ridiculous, it's all being meme-fied(ph). Joining us from our New York bureau is Don Caldwell. He's a reporter for KnowYourMeme.com, which, as you can imagine, tracks Internet memes. Welcome to the show, Don.

DON CALDWELL: Thanks for having me.

MARTIN: So, I'm going to put you on the spot: what is your definition of a meme?

CALDWELL: The word meme was actually coined in 1976 by evolutionary biologist Richard Dawkins. And he was trying to illustrate this concept of universal Darwinism. And it's the idea that anything replicates will undergo natural selection. And so he thought, well, maybe not just biological things under natural selection but maybe other things replicate like ideas. So, the word meme was coined as the cultural analog to a gene.

MARTIN: Wow. That's not where I thought you were going to go with that.

CALDWELL: But today, these days, we talk about Internet memes - viral videos or things we call image macros, which are captioned images, or just, you know, catch phrases and trends that typically spread on the Internet through sites like Red Head and Fourchan and Facebook and Twitter and Tumblr and that sort of thing.

MARTIN: So, we just heard a little bit of "Gangnam Style." This was listed as number one in your best memes of 2012. Did that surprise you that this particular meme has caught on so much?

CALDWELL: I mean, at the beginning, yeah. I was a little bit surprised by how big this was blowing up. But, I mean, the video was fantastic. I totally drank the Kool-Aid on this one.

MARTIN: So, other candidates were the McKayla is not impressed. This was one of the Olympic gymnasts, who we all know got caught making that smirk in the picture. And then everybody started doing it.

CALDWELL: Yeah. That one was really interesting because after it blew up, she took a picture with President Obama.

MARTIN: And he was doing the face.

CALDWELL: Yeah, he was doing the face.

MARTIN: You know your meme has caught on when the president engages.

CALDWELL: Yeah, that went full circle there, yeah.

MARTIN: As someone who tracks this stuff, what makes for a good meme? I mean, can you kind of predict, or does it feel random to you what catches on and what doesn't?

CALDWELL: There are certain things that do tend to spread more easily. For memes that share, like, on Facebook, for example, a lot of the time they'll say something about the person who's sharing it. So, what people think I do was another one we had on. It was gigantic. You probably saw it on your own Facebook newsfeed.

MARTIN: Yeah.

CALDWELL: And it was these little posters, about five or six custom images, that were used to say something about how certain people saw a job or expertise. And it was compared to how the person saw their own job or expertise and the often mundane reality of what it actually was. And people would share that because it was saying something about themselves.

MARTIN: So, any way to predict what the memescape will look like for 2013? Are there certain trends that you're looking out for and anticipating that someone will meme-fy(ph) a moment or a situation?

CALDWELL: Well, I think lately, like, we saw a rise in captioned images this past, you know, couple of years. The advice animals, as you'd call them, blew up. And I think that had to do with, you know, image hosting becoming cheaper online and captioning themselves became easier for people.

MARTIN: Wait, forgive me, I don't know this one. Advice animals?

CALDWELL: Advice animals - they're captioned images and they have, like, a stock character that represents some kind of archetype. One of the most famous ones is Scumbag Steve, and it was a photo of this, you know, thug-looking kid in a hallway. And the captions would be things like borrows your lighter permanently or pukes on something, disappears. He's a scumbag that we all knew earlier in our lives that we want to avoid.

MARTIN: So, I'm wondering how this affects you personally, Don. I mean, as someone who is inundated with memes all the time, it has to be a pretty spectacular meme for you to actually kind of laugh out loud, give a guffaw and forward it to your friends on Facebook.

CALDWELL: Maybe. I mean, I laugh all day at this stuff. I love my job. I am laughing at my desk all day long. It's great.

MARTIN: Don Caldwell is a reporter for KnowYourMeme.com. He joined us from our New York bureau. Thanks so much for being with us, Don.

CALDWELL: Thanks for having me on.

MARTIN: And you can check out the memes of the year on our website, npr.org.

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MARTIN: And you're listening to WEEKEND EDITION from NPR News. Transcript provided by NPR, Copyright NPR.