deep penetration
Sex where the person with a penis penetrates their partner balls deep— all the way to the base (sometimes called "hilting"), with the entire member inside the vagina or anus and only the testicles visible. Cross-section or x-ray shots often show the penis resting against the cervix, if not outright cervical penetration.
See also
The following tags are aliased to this tag: balls_deep (learn more).