The Immaculate Conception

A seventy-five year old guy, his hair is completely white, marries a twenty-two year old girl, and she gets pregnant.

Nine months later, he walks into the Maternity Ward. He says to the nurse, "Well, how'd I do?"

The nurse says, "She had twins."

He says, "Heh, heh, heh ... well, I guess that goes to show, that even if there's snow on the roof, there can still be fire in the furnace."

She says, "Well, then you'd better change filters. Both of the babies are black."