symmetrical docking
When two girls press their breasts (of roughly equal size) against each other. If there is a noticeable size difference, it is asymmetrical docking instead.
The male equivalent tag is pectoral docking.
Etymology
The term originates in GaoGaiGar, in which the combined form of Hyouryuu and Enryuu; Chouryujin, was released through a maneuver called "symmetrical docking" (post #132179). Later, other similar paired mecha performed the same combining maneuver.
In a Super Robot Wars 4koma (post #150779), the maneuver was likened to the action the tag now stands for.
See also
The following tags are aliased to this tag: /sd and breast_to_breast (learn more).
This tag implicates breast_press (learn more).