Head-on collisions between nuclei of different size at Fermi energies may give rise to extremely deformed dynamical regimes and patterns. Those latter, may suddenly turn into a stream of nuclear clusters, resembling collimated jets. This mechanism, which could be easily addressed in experiments, is simulated in the framework of stochastic one-body approaches. We employ the Boltzmann-Langevin equation to specifically address out-of-equilibrium conditions and handle dynamical fluctuations. An interesting interplay between surface and volume instabilities is discussed for the first time, leading to the appearing of stable and rather regular patterns of streaming clusters.