While oral sex accounts for a few cases. Other activities have not been show to cause AIDS, but theoretically could present some risk, because they can allow HIV-containing body fluids to get from one person to another. Studies show that HIV may be absorbed directly by cells in the mucous membranes. The safest activities are those that avoid any way in which HIV-infected blood semen or vaginal fluid can get from one person's body to another person's mucous membranes or bloodstream. Unprotected anal intercourse.
Sexual activities fall on a continum from high risk to risk-free.
Upper-middle range activities carry a minimal or indeterminate risk. Lower-middle range activities carry a theoretical risk. Activities at the bottom are completely safe.