The owner of a drug store walks in to find a guy leaning heavily against a wall.
The owner asks the clerk, "What's with that guy over there by the wall?"

The clerk says, "Well, he came in here this morning to get something for his cough.I couldn't find the cough syrup, so I gave him an entire bottle of laxative."

The owner says, "You idiot! You can't treat a cough with laxatives!"

The clerk says, "Oh yeah? Look at him, he's afraid to cough!"