(KCRG/CNN/Meredith) – It happens every year: a strange or unusual video challenge goes viral, and kids end up hurting themselves trying to participate.
Right now, the "salt and ice challenge" is the new trend.
You put salt on exposed skin and then add ice, holding both in place for as long as you can tolerate the pain.
Two teens in eastern Iowa are nursing severe burns after trying it out.
Tristen Tinnes will never forget the "salt and ice challenge" that severely burned his arm.
The 15-year-old tried the challenge with a group of friends Monday.
The challenge left Tinnes and one other with second-degree and third-degree burns on their forearms.
The two may need skin grafts to repair the damage.
Tristen's mom is taking care of him during what's become a physically and emotionally painful ordeal.
Starting about six years ago, plenty of others have taken the "salt and ice challenge," posting viral video reactions online.
One clip alone got more than 7 million views.
Doctors at University of Iowa hospitals and clinics warn that "salt and ice challenge" participants are basically giving themselves frostbite.
"It’s a chemistry experiment on your own skin," Dr. Thomas Granchi said.
The salt lowers the freezing temperature for water, and things can get really cold really fast.
"I certainly admire their curiosity. But, there are chemistry labs to study chemistry. Don't turn your body into a chemistry lab," Granchi said.
Tinnes said he's learned his lesson: viral online trends can stay online after the "salt and ice challenge" left its mark on him.
Tinnes will find out next week if he needs skin grafting. He may also have permanent scarring.