Guerrilla marketing is a marketing and advertising technique that uses unconventional methods and techniques to promote a product, service and/or organization.
Guerrilla marketing relies on unique and unorthodox practices to gain prospective customers' attention and interest. It is typically interactive in nature and tends to be less costly than typical marketing tactics.
Techopedia explains Guerrilla Marketing
Guerrilla marketing is inspired by guerrilla warfare, in which one side in an armed conflict employs unusual tactics to gain a strategic edge over its rivals.
Guerrilla marketing depends on unexpected techniques to catch potential customers' attention. The primary objective of this type of marketing is to gain the maximum exposure and revenue with the least amount of resources. For example, UNICEF promoted an awareness campaign about the issue of water quality in some developing countries by setting up a vending machine that sold dirty water in New York City. By providing thirsty pedestrians with bottles filled with water that appeared to be dirty and was labeled with water-borne diseases such as cholera, malaria and typhoid, UNICEF got its message across to people who may take the availability of clean water for granted. This simple stunt got people's - and the media's - attention.