It certainly is no gorilla, as the most common misconception might suggest.
Guerrilla Marketing is an unorthodox marketing and advertising strategy, used by creative and marketing teams to penetrate a difficult market or gain awareness through the power of ideas. Guerrilla Marketing campaigns are a brave and indirect method of promotion that relies on a smaller budget to generate a massive effect. It may include the use of creative disruption, “in-your-face” tactics, viral video marketing, word-of-mouth [WOM], or public displays [such as flash mobs, hidden cameras, interactive installations], to create engagement with an audience, otherwise difficult or costly to reach.