noun
double penetration
Explicit sexual term referring to simultaneous penetration of two orifices. Strongly vulgar; used in adult content and informal contexts.
そのアダルトビデオには二穴同時挿入のシーンが含まれている。
That adult video contains a double penetration scene.
Compound of 二穴 (two holes) + 同時 (simultaneous) + 挿入 (insertion). A straightforward descriptive term.