This is known as aversion therapy. Here, a patient is concurrently exposed to a stimulus, typically an addiction, and some form of discomfort. The idea behind this is that the patient will associate the addiction with unpleasant experiences. In this way, it is hoped that the patient will overcome his/her addiction. This sort of therapy has taken many forms. The more common form is for example to paint unpleasant-tasting nail polish on one's nails to discourage nail chewing. More extreme forms include electric shock therapy.