A joke from the keislowski's three colors trilogy 'Bleu'.. makes me laugh each time I see it.. it roughly goes like this..

There is this woman who gets paranoid and starts coughing loudly each time she visits a doc. The doc once gave her some pills and after consuming em she asked the doc whether they were pills to stop coughing.. the doc replied that the pills were the strongest laxatives in town, sneered at the patient and said "Now try coughing!"