vaginal
Pictures depicting vaginal penetration, whether by fingering, sex toys, tentacles, etc.
If, and only if, a penis is doing the penetrating, the image should also be tagged sex.
Note: Do not confuse this tag with Vagina/Pussy tag, which refers to female genitalia. If the character's vagina is clearly seen, It should be tagged with pussy.
See also
The following tags are aliased to this tag: vaginal_penetration and vaginal_sex (learn more).
The following tags implicate this tag: multiple_vaginal and vaginal_object_insertion (learn more).