A woman starts dating a doctor. Before too long, she becomes pregnant and they don't know what to do.

About nine months later, just about the time she is going to give birth, a priest goes into the hospital for a prostate gland infection.
The doctor says to the woman, "I know what we'll do. After I've operated on the priest, I'll give the baby to him and tell him it was a miracle."
"Do you think it will work?" she asks the doctor.
"It's worth a try," says the doctor.

So, the doctor delivers the baby and then operates on the priest.

After the operation he goes in to the priest and says, "Father, you're not going to believe this."
"What?" says the priest. "What's happened?"
"You gave birth to a child."
"But that's impossible!
" "I just did the operation," insists the doctor. "It's a miracle! Here's your baby."

About fifteen years go by, and the priest realizes he must tell his grown-up son the truth. One day he sits the boy down and says, "Son, I have something to tell you. I'm not your father."
The son says, "What do you mean, you're not my father?"

The priest replies, "I'm your mother. The archbishop is your father."