Culver City, California - First the tower of milk crates sways, then it collapses: On TikTok and social media, countless users have been posting and sharing videos of people trying – and above all failing – to climb and balance on stacked empty milk crates.

The so-called "Milk Crate Challenge" has spread like wildfire since the beginning of August, and has now prompted doctors to issue warnings to TikTok users considering taking part.

The aim of the challenge is to climb up and down a pyramid of stacked milk crates. But most of the videos show how participants lose their balance and then plummet onto the ground or fall onto the crates, often head first.

"With Covid-19 hospitalizations rising around the country, please check with your local hospital to see if they have a bed available for you, before attempting the Milk Crate Challenge," Baltimore's health department wrote on Twitter in response to the rising number of posts.

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Dislocated shoulder joints, torn ligaments and meniscus, broken wrists, and even spinal cord injuries are the most common results from this challenge going wrong, as Doctor Shawn Anthony from New York's Mount Sinai Hospital told the Washington Post.

"The orthopedic surgeries required to fix problems caused by this may fall under the umbrella of 'elective surgeries,'" tweeted George Gantsoudes, a pediatric orthopedic surgeon in Virginia.

Content depicting dangerous acts is prohibited on TikTok, according to its community guidelines. This includes dangerous games, dares, or stunts that could lead to injury.

While dangerous acts are forbidden on TikTok, that hasn't stopped tens of thousands from sharing and posting videos of viral challenges.

This also isn't the first time that TikTok users have risked their health for these challenges.

In the Tide Pod Challenge, participants had to bite down on detergent capsules. The Choking Challenge, in which participants intentionally fainted, was even reported to have claimed lives – like several others.

Nevertheless, videos of the new challenge have already clocked up millions of views on TikTok and other social networks, causing some laughs – and a lot of pain.