alpha_channel anal anal_penetration animal_genitalia animal_penis anthro anthro_on_anthro balls bent_over black_fur black_hair black_nose butt canine canine_penis crossybear_(artist) duo erection eyes_closed from_behind_position fur green_hair green_nose hair hi_res male male/male male_penetrating mammal multicolored_fur nude open_mouth penetration penis sex simple_background tongue tongue_out transparent_background two_tone_fur wolf