[Solved] The random assignment of subjects to experimental and comparison groups is not the same as random sampling of individuals from some larger population. Autoeroticism: The practice of achieving sexual pleasure through stimulation of one's own body. Penial-vaginal Intercourse: A sexual encounter characterized by the penis being inserted into the vagina. Genital Thrusting: A sexual behavior involving the rhythmic motion of the pelvis, often associated with the act of intercourse or sexual excitement. Interfemoral Intercourse: Movement of the penis between the partner’s thighs.