An Australian man claims to have found the answer to a question that has confounded people for decades: How do you drink a beer while wearing a lifejacket?

This video shows the man, called Rob, turning the jacket upside down and wearing it as an improvised 'diaper'.

When lifejackets are worn normally, it often restricts the user's neck and arms, making it difficult to sip from a bottle or a can.

But Rob's method leaves his upper body completely unrestrained, allowing him to knock back a beer as he bobs in the water.

An Australian, called Rob, has worked out how to wear a lifejacket and drink a beer - by putting it on upside down

The video starts with Rob explaining how to put the jacket on.

'W hat you do is you put a leg in here,' he says as he slips into the 'diaper'.

'And then you just float in the water,' a friend jokes in the background.

One of men on the boat with Rob and two women asks what he plans to do if the coastguard spot him trying out his new floating technique.

'I can see the coastguard pulling up and saying "sir you have your life preserver or your flotation device on upside down".'

Rob is seen grabbing a can of beer from a box and making his way over to the side of the boat

Rob then leaps into the water, carefully making sure to keep his beer above the surface

But Rob, who at this point is already taking his shirt off, insists that will not be a problem.

'You have no idea man, you're in the water and you just f***ing sit there. They won't f***ing do anything.'

Rob is then seen grabbing a can of beer from a box and making his way over to the side of the boat.

'I've got to watch this in action now. We're just waiting for you to float in the water,' the woman filming says.

Rob then leaps into the water, carefully making sure to keep his beer above the surface.

Triumphantly, he announces to the camera: 'Now who's the joker?'