They sing it at daycare: Baby shark, doo doo doo doo doo doo.

They sing it in their rear-facing car seats: Mama shark, doo doo doo doo doo doo.

They sing it at bath time and dinnertime and way past bedtime: Daddy shark, doo doo doo doo doo doo.

Parents of children under 4 know exactly what this is about. For everyone else, welcome to the inescapable cultural phenomenon that is “Baby Shark.”

The catchy children’s song has gone explosively viral, saturating the internet and the neural circuitry of toddlers the world over. 

It’s the latest pop culture trend to captivate a young audience – perhaps the youngest ever – fueled by animated, K-pop style YouTube music videos that have racked up more than 3 billion views.

The tune itself isn’t exactly new: It started as a simple nursery rhyme more than 20 years ago, a go-to singalong on school playgrounds and summer campgrounds. 

In 2015, it was reinvented as a series of whimsical music videos by Korean children’s entertainment brand Pinkfong. 

The most popular version features a lineup of cartoon sea creatures alongside singing and dancing Korean children.

For the song’s littlest fans, it is an irresistible, fantastical delight. For children’s entertainment marketers, it’s one more leap toward the globalization of childhood consumerism – mesmerizing prekindergartners who watch again and again on tablet and phone screens.

For parents, it’s a maddeningly infectious earworm that haunts at all hours.

“It was playing over and over again in my mind the other night,” says Lauren Astor, the mother of 4-year-old and 2-year-old boys in Los Angeles.

“I had to wake my husband up in the middle of the night because I had been dreaming and singing it in my sleep and couldn’t stop,” says Emily Hassenstab, an Omaha mother of a 2-year-old son.

Caroline Guthrie has been hearing it constantly since her 3-year-old daughter, Dottie, discovered it last year in the sidebar of recommended videos on YouTube Kids.

“For a while she was obsessed,” Guthrie says. “There were all these different versions, and she’d want to watch them one at a time in sequence. It was stuck in our heads all the time. My husband would be at work whistling ‘Baby Shark.’ It infiltrated us. It’s become part of our household language.”

The song has been a massive success for Pinkfong and its parent company, SmartStudy, which has created more than 100 videos based on “Baby Shark.” 

The most popular version alone has been viewed more than 1.6 billion times on Pinkfong’s YouTube channel, according to Jamie Oh, director of global marketing and partnerships at SmartStudy.

The tune, translated into 11 languages, has climbed to first place in children’s music on iTunes, Apple Music, Google Play and Amazon, Oh says. It has also inspired an onslaught of spinoff home videos shared under the hashtag #BabySharkChallenge, where people record themselves performing the song and dance.

Celebrity parents are in on the trend, too. References to “Baby Shark” have popped up on the social media feeds of Jimmy Fallon, Cardi B, Chance the Rapper, Tyra Banks and Kylie Jenner. 

Those widely viewed posts on Twitter and Instagram gave yet another boost to the easily shareable song’s worldwide popularity.

“A simple song that isn’t tied too radically to a given culture can, with the right technology, easily become global,” says Gary Cross, a cultural historian at Penn State University who specializes in modern childhood. “Children are not yet fully embedded in a culture, and they’re very adaptable to fads.”

The Washington Post