§ 30 You shall not sit down next to someone already sitting on one of the extra wide seats at the front of Norwegian buses
… Even if you are used to other places in the world where seats like this can easily fit three persons
Officially these are called “mother-and-kid- seats” or, unofficially, “big-people-seats”.
They are definitely not for two passengers who do not know each other.
This is one of the 100 Unwritten Norwegian Social Laws presented in our book "The 100 Unwritten Norwegian Social Laws"