RCW 59.04.050: Tenancy by sufferance—Termination.

Whenever any person obtains possession of premises without the consent of the owner or other person having the right to give said possession, he or she shall be deemed a tenant by sufferance merely, and shall be liable to pay reasonable rent for the actual time he or she occupied the premises, and shall forthwith on demand surrender his or her said possession to the owner or person who had the right of possession before said entry, and all his or her right to possession of said premises shall terminate immediately upon said demand.