If you want people to talk about your business on social media you have to give them something to talk about.
Coca Cola created a 2×1 Friendship Machine that gives you two cokes for the price of one if you were able to reach the 2 for 1 button. This button was placed high enough as to where you were not able to get from the ground. The machine is a creative way to stir up some user generated content around their brand.
Friendship is consistent with their standardized branding, and positive images and reinforcement help growth and strengthen the value of the brand.