For this poor chap, known as Brandon, fooling his brain into thinking he was on a roller coaster almost knocked him sideways.

Wearing a visor so all he can see is the virtual ride and listening to the sound of the clunking tracks, it only takes the first 'drop' for him to suddenly stumble and lurch sideways, to the amusement of his friend.

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'Whoa!' he shouts as he tries to stay on two feet. 'Oh my god.'

His friend, who is filming the whole experience, laughs uncontrollably as the virtual roller coaster ride sends his friend stumbling forwards and backwards.

At one point he nearly knocks the computer screen onto the floor.

'This is crazy, whoa,' he shouts.

Notes and comments on the hilarious clip, posted on Youtube.com, reveal the boys are from Mississippi, U.S., and were trying out a demo made by a forum member on MTBS3D.

The publisher, 'ibarakiprefecture', says: 'Yet another co-worker of mine wants to try the Oculus Rift. He probably should have sat down lol.'

Viewers can watch what Brandon's brain thinks he is experiencing on the computer screen.

He goes on to explain that not everyone has reacted in the same way; the most extreme reactions are from those who suffer from motion sickness.

The footage has drawn quite some attention from the online world.

At the time of writing, the video had already been seen by over half a million web-users.

ibarakiprefecture commented: I can't believe this has been viewed so much.

He adds: 'I hope you guys enjoy these reaction videos I've been recording. We are having a good time making these.'

At the end of the video he jokes to his friend: 'Can you do that on one foot?'