You have seen the pictures of the G20 summit in Hamburg. A bloke had to do some grocery errants. So he wrote a poster to get across the protestors, saying: "I am living here and just want to go shopping at Edeka" (name of the discounter)
He posted it on facebook. Edeka must have some good people monitoring the social media. Their answer was inmediate: "Stay at home - we'll bring you something."
Finally, the guy answered telling them that he wasn't a freeloader, but if Edeka wanted to do something they could take some food to people living in the streets.
Edekas answer was immediate: "Perfect, we'll do".
Now you can't make a better campaign. This was worth millions. And it just took minimal efforts.