We propose a simple set of equations of motion for the fictitious ensemble average particle, with the effects of the turbulence phenomenologically incorporated into a friction tensor. The components of this tensor reflect the perpendicular and parallel coupling to the bulk flow and are estimated from test particle studies in fluctuating homogeneous magnetoplasmas. The approach is extended to moderately inhomogeneous media, and illustrated with the behavior of bow-shocked lithium ions in the magnetosheath for distinct turbulence regimes.