rule 34 2016 abs anatomically correct anatomically correct penis animal genitalia animal penis anthro balls biceps big penis biped clayton haniger equine equine penis erection fasttrack37d flexing front view grey background greyscale hair half length portrait cock long hair looking at viewer male male only mammal medial ring monochrome muscular muscular male navel nipples nude pecs penis pepsi fa portrait pose sheath simple background smile snout solo standing watermark 2491842