Kids use a belt, rope or their bare hands to suffocate themselves to get a brief rush of euphoria and light-headedness.
Cops documented four cases this week.
Students at one high school reportedly posted a video on YouTube demonstrating the "game."
The Canadian GASP campaign (Games Adolescents Shouldn't Play) says anywhere from 25 to 1,000 young people die each year in the US from the "game," which also goes by the names the "fainting game," the "pass out game" or "space monkey."
"The plan is to release the pressure at just the right time before passing out in order to achieve the high. If they pass out first, the weight of their body pulls on the rope and they can die. There's also the chance of seizures, stroke or injuries from a fall," GASP's website says.
A lack of oxygen to the brain kills a large number of brain cells permanently, GASP says. Noticeable brain damage can occur within three minutes; after between four and five minutes, a person will die.