The rocks that are spreading have shocked many.
The fact that the breathalyzer gives a result is surprising to most people, but you don't have to worry about being affected.
There is alcohol in everything that has sugar in it and where there is some form of fermentation.
According to Tomas Jonsson, the alcohol needs to get into the blood for the ability to drive to be affected.
But that is not the case when you drink Christmas must.
- What happens in this case is that you get a contamination and the mouth alcohol disappears after just a few minutes.
If you drink Christmas must in the car and then get stopped at a police checkpoint, there is a risk that you will be accompanied into the station, says Tomas Jonsson.
- If you blow over the limit for drunk driving, it may happen that the police need to take you in for an evidence test.
But there the devices are so sophisticated that they detect whether it is oral alcohol or not, he says.
Watch as Morgonstudion tries out the Christmas must trend in the video above.