The fire challenge is a popular social media video series where kids douse themselves in some sort of flammable liquid and then set it on fire. The goal is to put out the fire before any damage takes place. Of course, it often results in serious injury to the participant. Aside from obvious external damage that can occur, damage to the lungs can occur from inhaling superheated air.
From what I can tell this challenge started somewhere around mid 2014 and has been popular since.
There are a number of stories with kids suffering from serious injuries from participating in this challenge. A couple are below.