Sisters of St Francis ...

A man is driving down a deserted stretch of highway and is astonished when he sees a  sign on the side of the road.

It reads:
SISTERS OF ST. FRANCIS
HOUSE OF PROSTITUTION
10 MILES

He thinks it was a figment of his imagination and he drives on without a second thought. Soon he sees another sign, which says:
SISTERS OF ST. FRANCIS
HOUSE OF PROSTITUTION
5 MILES

It begins to dawn on him that these signs may be for real...
Then he drives past a third sign saying:
SISTERS OF ST. FRANCIS
HOUSE OF PROSTITUTION
NEXT RIGHT

His curiosity gets the best of him and he pulls as directed.
On one side of the parking lot there is a stone building with a small sign next to the door reading:
SISTERS OF ST. FRANCIS

He climbs the steps and rings the bell.
The door is answered by a nun in a long black habit who asks,
"What may we do for you, my son?"
He answers, "I saw your signs along the highway, and was interested in possibly doing business."
The nun regards him coolly. "Very well. My son. Follow me."

The man is led through many winding passages and is soon quite disoriented.
The nun stops at a closed door and tells the man, "Please knock on this door."
He does as he is told and another nun in a long habit, holding a tin cup, answers the door.
This nun instructs him: "Please place $100 in the cup, and then go through that large wooden door at the end of this hallway. And be sure to pull the door behind you."

He gets $100 out of his wallet and places it in the second nun's cup. He then trots
eagerly down the hall and slips through the door, pulling it shut behind him. As the door locks behind him, he finds himself back in the parking lot, facing another small sign:
YOU HAVE JUST BEEN SCREWED BY THE SISTERS OF ST. FRANCIS.
Serves you right! Sinner !