rule 34 2021 animal genitalia animal penis anthro arms tied back groove balls biceps biped blurred background bodily fluids bound brown body brown fur brown hair chain leash chains closed eyes collar cum cum on ground equid equine equine penis erection flared penis fur genital fluids genitals hair hands behind back hi res kneeling landysh leash legs tied male mammal medial ring muscular muscular anthro muscular male penis rear view restraints shoulder blades solo spank marks 5354929