As expected from the name, guerilla advertising is the more unconventional way to marketing. Guerilla advertising has a shock factor. To engage in this marketing technique, you simply take an existing item in public, and then you add to the environment. Be careful about how you go about the campaign because it can be viewed as vandalizing public property. 

 You may use the following techniques for your guerilla advertisement: 

• Stencil graffiti or repeated works of street art 
• Reverse graffiti where marketers remove dirt from the surfaces to create natural-looking messages 
• Stickers  
• Undercover Marketing, also known as stealth marketing