Tasmanian's

[GraemeMonro]

Two Tasmanian"s were sitting around talking one afternoon over a cold beer.After a while the first Tasmanian says to the second, "If I was to sneak over to your house and make love to your wife while you was off fishing’, and she got pregnant and had a baby, would that make us related?”The second Tasmanian crooked his head sideways for a minute, scratched his head, and squinted his eyes, thinking real hard about the question. Finally, he says, "Well, I don"t know about related, but I reckon it’d make us even."

[MadMuz]

It probably wouldn"t matter anyway, they are probably all brothers and sisters anyway?