The popularity of personal devices has been creating a new location-based content era, where users produce, share and access content anytime and anywhere. Mobile devices in the same area can cooperate to each other by using a Device-to-Device (D2D) communication and maximize the usage of network resources and allow the creation of new applications and experiences. In this paper, we investigate the dynamics of physical proximity of peers in a long-term study. We used one year of collected data from social media for an analysis of spatiotemporal features of how users encounter each other and the opportunities for content offloading in cellular networks. The results provided insights about the regularity of encounters, the role of routine and other spatial characteristics.