A Nun walks into a bar and ask's the barman for a large bottle of whiskey. Everyone stopped and stared at her. "Nun's don't drink," said a man at the bar

"Oh No it's not for me. It's for Mother Superiors constipation" the Nun said

So the Barman gave her the whiskey and she walked out.

Later that night, after the barman had locked up the bar he went to find the Nun shit-faced in a local park.
"I thought that was for your mother superiors constipation" he said.

"It is," said the Nun, "when she sees me she'll shit!"