A socially responsible consumer is a consumer who cares about the social impact that the products he buys have on the world around him. Socially responsible consumers avoid products that they think harm society. Instead, they buy goods and services from companies that they believe do a better job of taking care of the world.
An example of such a behaviour would be a person who shops in small stores as opposed to shopping in supermarkets, because he believes that it is important to support local businesses. Another example is that of someone who buys free trade coffee, in order to ensure that his purchase does not have a negative impact on coffee farmers around the world.