anal intercourse
insertion and thrusting of the erect penis into a person's anus, or anus and rectum, for sexual pleasure
en-GB/ˈeɪnəl ˈɪntəkɔːs/
en-US/ˈeɪnəl ˈɪnɚˌkɔɹs/
insertion and thrusting of the erect penis into a person's anus, or anus and rectum, for sexual pleasure