Curing a Cough

The owner of a drugstore arrives at work to find a man leaning heavily against a wall. The owner goes inside and asks his clerk what's up.

- He wanted something for his cough, but I couldn't find the cough syrup - the clerk explains:

- So I gave him a laxative and told him to take it all at once.

- Laxatives won't cure a cough, you idiot - the owner shouts angrily.

- Sure it will - the clerk says, pointing at the man leaning on the wall:

- Look at him. He's afraid to cough.