He asks the clerk, 'What's with that guy?'
Clerk says, 'He came in with a bad cough and asked me for cough medicine. We were out of cough medicine, so I gave him a whole bottle of laxative instead.'
The guy says, 'What?! You can't treat a cough with laxative!'
The clerk replies, 'Of course you can! Look at him. He's afraid to cough!'