If you haven't heard of NekNomination, you might want to check your Facebook account—or your child's.
The dangerous social-media drinking game that got its start in Australia has spread to England, Ireland and now the United States, prompting the deaths of at least four people in their 20s and younger, according to ABCNews.com.
To play Neknomination, participants must "neck"—another slang term meaning "to chug"—an alcoholic drink and post it on a social-media network, such as Facebook or Twitter. Players then "tag" or call out other friends to play the game, too, often goading them to up the ante within 24 hours.
In fact, according to the news site, players have even drunk their drink while driving or doing backflips. They've also added ingredients to drinks such as protein powder and engine oil.
"The game’s encouragement of participants to outdo each other with ever more reckless stunts brings with it significant risks of alcohol-related harm including acute intoxication, accidents and injury," Rosanna O'Connor, director of alcohol and drugs at Public Health England, told ABCNews.com via email.
Four people so far have died while playing the game.
Isaac Richardson, 20, of England, died earlier this month after drinking wine, vodka, whiskey and beer, according to The Telegraph. Another U.K. resident, Stephen Brooks, 29, died after drinking a pint of vodka.
Ross Cummins, 22 (pictured above), and Johnny Byrne, 19, of Ireland, also died playing the game.
Parents, be aware.
"It has already cost lives and we would advise anyone against taking part in the game to avoid putting themselves in a potentially dangerous situation," O'Connor continued over email.