Cellular resources are expensive and should be saved whenever possible. In this paper, we propose SCoD, a resource saving strategy that draws on the mobility of users to reduce the number of cellular transmissions. The idea is to postpone a transmission in order to maximize its benefits in terms of users located in the same cell. We exploit the delay tolerance of content combined with the natural tendency of users to get together in the same locations; by relying on multicast communications, we can then reduce the number of transmissions required to satisfy all requesting users. SCoD relies on previous observations to determine, in an adaptive way, the number of users that should trigger a multicast transmission in a cell. We evaluate SCoD and compare it against other strategies by running trace-driven simulations based on real-world mobility datasets. We also compare SCoD with an Oracle, which gives the best case but is unfeasible as it relies on the knowledge of future displacements of nodes. The results show that SCoD covers 100% of the users while consuming almost as few resources as the Oracle.