In a framework of classical dynamics we develop a new classification scheme for multi-electron trajectories in terms of sequences of binary collisions. We confirm the Wannier threshold law for four-body break-up of Lithium and show that our theoretical results are in excellent agreement with recent experimental ones. Surprisingly, for the angular distribution of the ionized electrons we do not find a preferential symmetric break-up with an interelectronic angle of 120^{\circle} as predicted by Wannier's theory. However, the angular pattern is consistent with our classification scheme of binary collisions.