Unless you've been living at the bottom of the sea, like an actual shark, there's a good chance you've heard the "Baby Shark" song recently.
Think you haven't? Ask yourself if you've heard anyone anyone sing "Do Doo Do Do Doo Do Do Do" for no reason at all in the past month. If you have, then you, too, have been swept up into Baby Shark Fever.
The song started as a simple nursery rhyme uploaded to YouTube by Korean education company Pinkfong.
But the adorable Korean video, which features two super cute kids miming the actions to a song about a shark family, has taken over the world.
K-pop stars got in on the action, with some of the industry's biggest stars performing it live at their concerts, much to the delight of the crowd.
Then, the song made its way overseas, where American TV show hosts like Ellen and James Corden have presided over Baby Shark singalongs.
But it's not only celebrities getting in on the action.
People have started doing the #babysharkchallenge, in which they find creative ways to sing and dance to the tune.
One of the most popular seems to be during warmups at gymnastics classes, where young gymnasts really get to show off their best imitation of shark jaws.
Others have made sure they're in the right head gear before trying the Baby Shark challenge.
There's even an R&B; remix from Desmond Dennis that does a great job at highlighting how absurd it is that we're all singing a song about a large shark family.
The phenomenon has sparked countless memes.
Some viral songs fade into obscurity pretty quickly, but this one seems determined to stick around for at least a little while longer.
That's great news if you love it. And if you hate it? Well, you doo do do doo do do do you!