The need to exploit the physical vicinity of mobile users in social platforms has never been more evident as increasingly more users access social networks from mobile devices. The effect of online social connections has already been shown as instrumental in spreading content and influence via social cascade. In this paper, we examine the phenomenon of social cascade when confined to the user's physical vicinity. We examine the intersection between patterns of both social cascade and physical colcoation. We combine traces of user mobility with models of online social cascade and show that content propagated via social cascade on online social networks are likely to be already cached on the devices of colocated peers.