(I probably picked this one up from Mudcat)
Father Murphy, a missionary, was the only white man within a thousand
miles of Ambungu when the chief's daughter gave birth to a white baby.
The medicine man accused Father Murphy of misbehavior but was told "Don't jump to conclusions, it's simply a genetic abberation".
When the medicine man failed to understand this Father Murphy took him up the hill and pointed towards a herd of sheep below saying, "Look at all of those white sheep and theres a single black one in the middle". The medicine man replied "You don't mention the sheep to anybody and I won't mention the baby".