Geodesic acoustic modes (GAMs) in a tokamak excited by, for example, energetic particles can create a direct energy channel from energetic population to turbulence. In this paper, the ability of GAMs to further convert their energy into large scale motion such as zonal flows is investigated. The simplest case of GAMs, neglecting the effects of normal curvature, Alfvén wave effect and drift effects, is considered. It is shown that such GAMs are stable with respect to generation of zonal flows.