A dangerous drinking game called "Neknominate" that is sweeping Australia and New Zealand has taken an even more extreme turn.

Hair-raising videos have emerged of drinkers dangling precariously from helicopter as they chug bottles of beer, over a lake in a park. Disclaimer: The videos may contain swearing.

The game - which was thought to originate from students - involves people videoing themselves drinking large quantities of alcohol in ridiculous situations, before nominating a friend to do the same.

A Facebook group, called Neknominate, has over 12,000 likes already - although it was set up just two weeks ago. It shows people drinking enormous amounts of spirits, including vodka and bourbon.

Authorities have deemed the game to be "totally inappropriate" and fear for the safety of the young people involved. As people try and "out do" each other in the game, it is becoming increasingly dangerous and more extreme.

Clips include a man drinking a beer before nailing his testicles to a table, then drinking another one.

In another, a skateboarder chugs beer through a pipe - while riding down a steep hill, passing oncoming traffic.

Earlier in the week, police in Australia confirmed they had interviewed a 21-year-old man, who was seen travelling in the boot of a car before "downing" a bottle of beer and getting back into the boot.

Another trend concerning authorities is "skidnominate", a dangerous escalation of the drinking game where participants film themselves doing burnouts, skids and other stunts in their cars.

In the video below, a man can be seen riding a motorbike on a main road, while drinking a can of beer.

On social media, the hashtag "neknominate" began trending in the UK in January 2013. It has since been growing in popularity around the world, but seems to have recently found a large following among young males in Australia.

Professor Michael Farrell, director of the University of New South Wales' National Drug and Alcohol Research Centre, condemned the game as potentially deadly.

Speaking to the Sydney Morning Herald, he said: "It's like Jackass and that type of wild behaviour, and it's not necessarily very impressive."

He added: "In general it looks like it could get people into a lot of trouble, with a lot of pressure to drink. It's competitive, heavy drinking, and that tends to end up with people coming to serious grief through alcohol poisoning."