A Nun Joke

From an email my Uncle sent:

A man is driving down a deserted stretch of highway
when he notices a sign out of the corner of his eye....
It reads:

SISTERS OF ST. FRANCIS
HOUSE OF PROSTITUTION
10 MILES
He thinks this is a figment of his imagination and
drives on without second thought.....

Soon he sees another sign which reads:
SISTERS OF ST. FRANCIS
HOUSE OF PROSTITUTION
5 MILES

Suddenly he begins to realize that these signs are
for real and 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 into
the drive... On the far side of the parking lot 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.....'
'Very well my son. Please follow me.' He 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 so and another nun in a long habit, holding
a tin cup answers the door... This nun instructs, 'Please
place $100 in the cup then go through the large
wooden door at the end of the hallway.'

He puts $100 in the cup, eagerly trots down the hall
and slips through the door pulling it shut behind him.
The door locks, and he finds himself back in the
parking lot facing another sign:
GO IN PEACE.
YOU HAVE JUST BEEN SCREWED BY THE
SISTERS OF ST.FRANCIS.