For this demo, we present an implementation of the FairPlay framework for secure two-party function computation on Android smartphones, which we call MobileFairPlay. MobileFairPlay allows high-level programming of several secure two-party protocols, including protocols for the Millionaire problem, set intersection, etc. All these functions are useful in the context of mobile social networks and opportunistic networks, where parties are often requested to exchange sensitive information (list of contacts, interest profiles, etc.) to optimise network operation.