A Colorado mom is having her life threatened online after one of her TikTok videos went wildly viral.

The video features a controversial method of teaching swimming to infants – having an instructor throw them into a pool – and the online outrage has been swift and overwhelming.

The mother who recorded the video, 27-year-old Krysta Meyer of Colorado Springs, has only been on TikTok since February, recording videos that would get a couple thousand views at most.

But a video she took of her infant son's swimming lesson suddenly rocketed her to viral infamy in just a few days: as of yesterday, the video has been viewed more than 51 million times on TikTok and 20 million times on Twitter.

Why? Because it shows 8-month-old Oliver being tossed into a pool by his instructor like a sack of potatoes.

In fairness to Ms. Meyer, this is an extremely common method for teaching babies to swim. The focus is not so much on learning to backstroke, but on survival: should a baby, say, fall into a pool, the thinking goes, they will know how to get themselves to air so that they can survive until they're rescued. This type of class is in fact called an "infant survival class."

Speaking to BuzzFeed News, Lauri Armstrong, co-owner of the Little Fins Swim School where Meyer's son takes classes, explained it this way:

"The whole premise behind what we do is safety. We teach 8-month-olds to assess their situation and find an exit strategy [in water]. I know it seems crazy."

The classes teach infants how to flip over and float on their backs should they fall into a body of water, using their muscle memory from floating in the womb.

There isn't exactly consensus on the method though: As BuzzFeed reports, British advocacy organization Birthlight has argued that the practice is traumatizing, and the American Academy of Pediatrics has said since 2000 that there is no evidence of the method's efficacy.

Which may in part explain why Meyer's video has angered some people – to the point of threatening her with violence. As she told BuzzFeed:

"A lot of people are seeing a kid being thrown into the water and thinking, That's not good! You shouldn't be doing that! I've gotten death threats. I've had people tell me I'm the worst kind of mom, that I'm endangering my children, that I'm traumatizing them."

And the Twitter response partly bore out Ms. Meyer's claims – many people were upset by the video.

But many others were, like little Oliver's instructor, totally on board with the method.

And of course, this being Twitter, there were jokes!

While methods like Little Fins' may be a bit much for some parents, swimming skills for small children are vitally important according to the American Academy of Pediatrics, which last year recommended that all children over one year of age should learn to swim.