Chainsaw prank backfires while attempting to copy viral video

A sleeping teen nearly had his hand lopped off after some friends woke him up with running chainsaw.

The 18-year-old German was taking a nap on Christmas Day in the town of Wickede when a group of friends, aged between 15 and 22, devised an ill-thought out prank.

Copying a viral video they had seen online, they fired up a chainsaw next to the sleeping man.

The startled teen threw his arm out, straight into the sharp chain.

“(He) was so frightened that he tried to push the blade away, and was badly injured to his left hand,” police spokesman Wolfgang Lueckenkemper said.

What the attempted jokesters did not realise was the original viral video had safety measures.

The original pranksters keenly realised there was no need for a chain to be on the chainsaw, and removed it before waking up their mate.

In the German version, the chain was left on.

The 22-year-old wielding the machine told police he had switched on the chain brake, however the chain had still spun.

Police do not believe the incident intended to harm the victim, however he ended up in hospital with serious injuries.

Several of his friends suffered shock.

The video of the near-amputation has been kept by police, who are expected to charge the 22-year-old, WAZ.de reports.