A Nip o' Gin
A nun walked into a liquor store and asked for a bottle of gin. The guy at the counter gave her a look as he handed her the bottle. Noticing the strange look, she said to the guy, "This gin is for the Mother Superior's constipation."
The clerk shrugged and gave it no more thought.
About an hour later he closed up shop and was walking home when he came upon the same nun sitting on the curb with an empty bottle. She looked to be three sheets to the wind in a hell of a gale.
Shocked, the guy exclaimed, "Why, sister! You said that gin was for the Mother Superior's constipation."
"It is," the nun chuckled. "She's really going to shit when she sees me!"