One day there was four nuns in line for confessional. The first nun said, "Forgive me, father, for I have sinned."

He asked how. She said "I saw a man's private part."

He told her to wash her eyes with holy water. The second nun comes in and says, "Forgive me, father, for I have sinned."

He asked how. "I touched a man's private parts."

He told her to wash her hands in holy water.

Just then he heard the third and fourth nun fighting. He asked why they were fighting.

The fourth nun said, "I'm not going to put my mouth in the holy water after she's sat in it."
 

Another version of the same joke

A train hits a bus load of nuns and they all perish.

They are all in heaven trying to enter the pearly gates past St. Peter. He asks the first nun, sister Karen, "Have you ever had any contact with a penis?"

The nun giggles and shyly replies, "Well once I touched the head of one with the tip of my finger." St. Peter says, "OK dip the tip of your finger in the holy water and pass through the gate."

St. Peter asks the next nun the same question, "Sister Elizabeth have you ever had any contact with a penis?" The nun is a little reluctant to reply but she says, "Well once I fondled and stroked one." St. Peter says, "Okay dip your whole hand in the holy water and pass through the gate."

All of a sudden there is a lot of commotion in the line of nuns, one nun is pushing her way to the front of the line. When she reaches the front of the line, St. Peter says, "Sister, sister what seems to be the rush?"

The nun replies, "if I'm going to have to gargle that water, I want to do it before sister Mary sticks her ass in it!"