Six friends are gathered at a pub. They have in front of them three 12-pint tankards full of beer, and an empty 5-pint mug.

Since they are still sober, they quickly calculate that they have 36 pints for the six of them, which comes to an even 6 pints per person.

How can they divide the beer equally with the containers they have available?

Note: For the purposes of the problem, assume that the pub does not have any pint glasses, and the six friends will have to drink from the four available containers.