Guerrilla marketing 

It was originally a marketing strategy in which low-cost, unconventional means including the use of graffitti,  , flyer posting, etc. were used in a (generally) localized fashion to draw attention to an idea, product, or service. Today, guerrilla marketing may also include promotion through a network of individuals, groups, or organizations working to popularize a product or idea by use of such strategies as flash mobs, in ternet or marketing.

Guerrilla marketing was initially used by small and medium sized businesses, but it is increasingly being adopted by business. The concept of guerrilla marketing rises from an unconventional system of promotion that relies on patience, energy, and imagination rather than a big advertising budget. Typically, guerrilla marketing campaigns are unexpected and unconventional, potentially interactive, with consumers targeted in unexpected places. The objective of guerrilla marketing is to create a unique, engaging, and thought-provoking concept to generate buzz.

Guerrilla marketing involves unusual approaches to advertising, such as targeted promotional-driven encounters in public places, street giveaways of products,  stunts, flash-mob presentations, or any unconventional marketing intended to get results and create a memorable brand experience. Modern approaches to guerrilla marketing often utilize mobile technologies. This enables advertisers to engage consumers emotionally, and often enough, to hopefully cause a campaign to turn viral, thereby realizing maximum returns on a relatively low initial investment.