This paper presents OBN, a universal opportunistic ad hoc networking model particularly intended for smart mobile devices. It enables fast and lightweight data dissemination in wireless community networks through the utilization of universally-available wireless network identifiers. As a ubiquitous alternative to the publicly-limited ad hoc networking interfaces, it resolves many of the peer-to-peer data forwarding issues with smart beacon advertisements. Opportunistic beacons of the model require neither association nor connection for data sharing, instead exploit wireless network identifiers as message carriers. Our applicability tests on both real-world setups and simulations indicate the soundness of the model. Providing a high data dissemination performance in highly dense and highly mobile environments, OBN can be readily integrated to numerous mobile participatory sensing applications without requiring any specialized setup.