Sisters of mercy

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 MERCY HOUSE OF PROSTITUTION - 10 MILES.

He thinks it was just a figment of his imagination and drives on without a second thought. Soon, he sees another sign which says:

SISTERS OF MERCY HOUSE OF PROSTITUTION - 5 MILES

He realizes that these signs are for real. Then he drives past a third sign saying:

SISTERS OF MERCY 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 somber stone building with a small sign next to the door reading: SISTERS OF MERCY

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 as he is told and this door is answered by another nun in a long habit, holding a tin cup. This nun instructs, "Please place $50 in the cup, then go through the large wooden door at the end of this hallway."

He gets $50 out of his wallet and places it in the second nun's cup.

He 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:

GO IN PEACE, YOU HAVE JUST BEEN SCREWED BY THE SISTERS OF MERCY.