But sexual abstinence means different things to different people. One in three students reported that oral contact with another person's genitals was abstinence. However, when a heterosexual couple has anal intercourse, pregnancy is possible if the man's penis slips and enters the woman's vagina instead of anus. Of course, many students greatly lower their risk of STDs by using latex condoms during oral and anal sex. As a health educator, I'm encouraged to see more students concerned about staying healthy.
Many students enjoy fulfilling relationships without any sexual activities at all.
Other abstinent students express themselves through fantasy, touch, massage, mutual masturbation, and other means as a way of avoiding intercourse. It sounds like your roommate may be having some fun with the safer methods of sexual expression yet considers himself sexually abstinent because he doesn't have intercourse of any kind.