rule 34 anal anal knotting anal sex animal genitalia animal penis balls bodily fluids canid canine canis cum dasyuromorph domestic duo feral feral on feral furry only genital fluids genitals hemipenes knotting luca male malemale male penetrated male penetrating male penetrating male mammal marsupial marsupial penis multi genitalia multi penis no humans paws penetration penis sex thylacine 4112016