Vow of Death

Original title: ผีไม้จิ้มฟัน

Directed by Piyapan Choopetch

Four high-school friends who always misbehave and never focus on school. When the time for their college entrance exams comes along, all of them decide they'll need some special help in order to pass. They visit a holy banyan tree and pray for themselves to easily pass the exams.