A pharmacist walked into his shop to find an old man leaning against the wall.
"What's wrong with him?" he asked his assistant.
"He came in for cough syrup, we had none so I gave him an entire box of laxatives."
"You idiot" said the chemist, "You can't treat a cough with laxatives."
"Of course you can" the assistant replied, "Look at him.........he daren't cough now!"