Rule 34 Dev - 2023 animal_genitalia animal_penis azusagp balls brown_penis close-up digital_media_(artwork) equid equine equine_genitalia equine_penis erection feral feral_only fully_sheathed genital_close-up genitals horse male male_only mammal nude penile penis penis_close-up reference_image sheath simple_background text|10057679712