Description Of Behavior Mairil And Nyempet Former Santri And Santri On PreventionOf HIV/AIDS in The Boarding School; Mairil phenomenon and nyempet includinghomosexual genital interfemoral ie salvation squeeze in between the thighs . The research aims to analyze the knowledge, perception, experience and other factors on students doing mairil nyempet in boarding schools and the prevention of HIV / AIDS. The research uses a qualitative approach. The subjects were selected by purposive sampling as many as six people, consisting of three former students and three students who have done mairil and nyempet in boarding school. Data collection techniques using in-depth interviews, analysis of data through content analysis. Pupils do mairil and nyempet since settled in boarding schools from the age of 13-17 years, usually done at night, in the room in almost every night. Pupils do mairil and nyempet in schools on the basis of consensual and there is also the force. Cause mairil the homogeneous environment. Pupils learn that behavior and nyempet mairil haram and there is no penalty and the rules of conduct and nyempet mairil in boarding school. Students assume that there are no health effects they experienced as just sex to squeeze between the thighs without entering into the rectum.