John was a clerk in a small drugstore but he was not much of a
salesman. He could never find the item the customer wanted. The
drugstore owner had had about enough and warned John that the next
sale he missed would be his last.

Just then a man came in coughing and asked John for their best cough
syrup. Try as he might John could not find the cough syrup.
Remembering the owner's warning John sold the man a box of Ex-Lax and
instructed him to take the entire box all at once. The customer
immediately consumed the entire box in the store and then walked
outside and leaned against a lamp post. The drugstore owner had seen
the whole thing and came over to ask John what had transpired.

"He wanted something for his cough but I couldn't find the cough
syrup. I substituted Ex-Lax and told him to take it all at once."
John explained.

"Ex-Lax won't cure a cough" the owner shouted angrily.

"Sure it will" John said, pointing at the man leaning on the lamp
post. "Look at him. He's afraid to cough."