Rule 34 Dev - 2017 anal anal_sex anthro balls blush closed_eyes duo echidna erection furry green_eyes hedgehog knuckles_the_echidna krazyelf male mammal monotreme nude open_mouth partially_submerged partially_underwater_shot penetration penis sega sex sonic_*(series) sonic_the_hedgehog sonic_the_hedgehog_(series) swimming underwater underwater_sex water yaoi|933511