A chemist walks back into his shop after a short break and sees a man leaning against the wall.

"What's wrong with him?" he asks his assistant

"He came in for cough syrup but I couldn't find any so I gave him an entire bottle of laxatives" replied the assistant.

"You f----kn idiot" exclaims the chemist, "you can't treat a cough with laxatives"

"Of course you can" replies the assistant, "look at him, he's too f---kn scared to cough"