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. SERVES YOU RIGHT, YOU SINNER.

As a Catholic Irishman, I'm not supposed to laugh at what I found to be a hilarious joke. Joecool, it will be on your head if I go to hell! {It will not be necessary for certain people on this site to suggest that's where Irishmen belong)