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. Bob,
 the 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 he ask John for their best
 cough syrup. Try as he might John could not find the cough syrup.
 Remembering Bob's warning he sold the man a box of Ex-Lax and told
 him to take it all at once. The customer did as John said and then
 walked outside and leaned against a lamp post. 
 
 Bob 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," Bob shouted angrily. 
 
 "Sure it will," John said, pointing at the man leaning on the lamp
 post. "Look at him. He's afraid to cough!"