This is how it all begins - a nomination followed by cocktails. The game is called Neknominate - and it's thought to have originated in Australia.
But what started for some as a game has already begun to claim lives - at least four victims, all men under 30. Some reports say five have died around the world.
"This is a lethal game. The point about alcohol is that it affects your ability to recognize that you're in danger. And it absolutely affects your ability to react to danger. So we have a double whammy," said Dr. Sarah Jarvis, Medical Advisor, Drinkaware.
The premise of the game is simple. People film themselves neking - or downing a large drink, eye-raising concoctions of alcohol sometimes mixed with other things. They then post the video on social media. After that, they nominate a friend to outdo them. If the nominee doesn't respond, they are ridiculed on their Facebook wall or on Twitter.
Each nomination becomes more daring and outlandish. It started as exhibitionism, with a woman stripping in the supermarket and downing a drink. Challenges have included riding a horse in a shopping center parking lot. A Canadian man was pulled behind a car on a snowboard. But the bravado has escalated into extreme cocktails; one mixes alcohol with a dead mouse, among other things. Another saw two guys chug hot sauce with 89 percent absinth.
"Alcohol in teenagers can be very dangerous. They don't have a lot of experience, they don't know what they're limits are and by the time they've drunk too much it's often too late," said Dr. Richard Besser.
Brian Viner, whose own son has played the game, says responsibility must come from Facebook, which still today displays advertisements next to videos of people taking part in the challenges. Viner said his son was nominated and pressured to play the game but drank water instead of vodka so as not to harm himself.
"Crossed with him but more crossed with the social media involved and the way this game has just spread. The whole thing is madness and it needs some kind of sharp and swift action on the part of these social networks to stop it," Viner said.
In a statement to CNN, Facebook said, "We do not tolerate content which is directly harmful, for example bullying, but behaviour which some people may find offensive or controversial is not always necessarily against our rules. We encourage people to report things to us which they feel breaks our rules so we can review and take action on a case by case basis."
But to stop this once and for all, Jarvis says Facebook must recognize its own role in the game.
"It's very difficult in this day of personal liberties to say that Facebook shouldn't be condoning this or taking these videos offline. Personally, I would like to see that happen. Frankly, if the thrill wasn't there, your mates weren't seeing you, I expect it would very rapidly fizz out," Jarvis said.