pussy sandwich
When two girls lay on top of each other, with their pussies together, clothed or not. This may involve tribadism, take your pick, or cooperative grinding. The two characters' rears are usually facing the viewer.
Examples:
Danbooru post #2131637, Danbooru post #7147156, and Danbooru post #5060990
Posts like Danbooru post #7157059 should not have this tag.