Treating a Cough

The pharmacist walks into the store to find a guy leaning heavily against a wall. He asks the clerk, "What's with that guy over there by the wall"?

The clerk responds, "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 laxatives."

The pharmacist yells, "You can't treat a cough with a laxative!"

The clerk responds, "Of course you can! Look at him, he's afraid to cough!"