The tenant is having a party
The landlord can receive complaints from the neighbours about the tenant having a party, and it being bothersome for the neighbours.
It is initially the landlord's responsibility to make sure that there is peace and order at the residence. The tenant on the other hand must follow ordinary house rules, and as such secure peace and order. This means that the landlord can send a warning to the tenant if they have had a party that was bothersome for the neighbours.
The tenant has exclusive right of use over the residence, but if the tenant is having a party, it must be held in such a way that it does not entail breach of ordinary house rules.
The Tenancy Act section 5-2 (Norwegian)