Parents can't get it out of their heads and kids can't stop singing it. Did we mention there's also a challenge taking over social media?

Yep, we're talking about "Baby Shark," the kids song from years ago that's making a comeback. In fact, it's so popular now that it's jumped into the Billboard Hot 100 chart, swimming close to the top 30.

Now, this isn't a new song from Korean kids channel Pinkfong. .

Just take a look at the date stamp on the YouTube video and you'll see it says 2016. You'll also see views topping a billion.

The "Baby Shark Dance" video posted to YouTube by Pinkfong in 2016 has been viewed over 2 billion times.(PINKFONG/YouTube) The "Baby Shark Dance" video posted to YouTube by Pinkfong in 2016 has been viewed over 2 billion times.

But "Baby Shark" and its lyrics are timeless: "Baby shark, doo doo doo doo doo doo."

The song is repetitive and catchy but it was the video that started an online craze.

The recent push into the States can be attributed to celebrities embracing the song, like Ellen DeGeneres and LeBron James.

As for Pinkfong, it boasts 14 million subscribers around the globe, in languages that include Korean, Japanese, Spanish, Russian, Mandarin, Thai and English.

One of its latest songs, "Jungle Boogie," is similar to "Baby Shark" in its catchiness and educational value for kids.