This practice is usually done when someone go to a place that their not used to go. Dayu actually mean go away, Bari is rooted from the Ilocano word bakir which means a greepy or far place. Ilocanos say Dayu-dayu, bari-bari to sent out spirits that might harm them while they are in their way going to the place they’re not used to go.
This ilocano tradition is usually done after the burial of the member of the family where in they wash their head and usually done in the sea or river. It is said that this is done in order for the family members to wash away the pain of losing someone. And to wash away the sickness and bad luck associated with the death of the family member.
This practice is usually done when they are on their way going home from a greepy or far place. Ilocanos are saying Agawidun (your name), di ka agbatbati (your name) because they believe that when you don’t say this word while going home your souls might left behind. They are telling their souls to come with them. Agawidun actually mean go home, and di ka agbatbati means don’t stay there or you come with me.