Currently, many users of Social Network Sites are insufficiently aware of who can see their shared personal items. Nonetheless, most approaches focus on enhancing privacy in Social Networks through improved privacy settings, neglecting the fact that privacy awareness is a prerequisite for privacy control. Social Network users first need to know about privacy issues before being able to make adjustments. In this paper, we introduce Friend Inspector, a serious game that allows its users to playfully increase their privacy awareness on Facebook. Since its launch, Friend Inspector has attracted a significant number of visitors, emphasising the need for better tools to understand privacy settings on Social Networks.