  Using the hydrodynamic model in the electrostatic approximation, we describe
the formation of graphene surface plasmons when a charge is in motion either
perpendicular or parallel to a graphene sheet. In the first case, the
electron-energy loss (EEL) spectrum of the electron is computed, showing that
the resonances in the spectrum are linked to the frequency of the graphene
surface plasmons. In the second case, we discuss the formation of plasmonic
wakes due to the dragging of the surface plasmons induced by the motion of the
charge. This effect is similar to Coulomb drag between two electron gases at a
distance from each other. We derive simple expressions for the electrostatic
potential induced by the moving charge on graphene. We find an analytical
expression for the angle of the plasmonic wake valid in two opposite regimes.
We show that there is a transition from a Mach-type wake at high speeds to a
Kelvin-type wake at low ones and identify the Froude number for plasmonic
wakes. We show that the Froude number can be controlled externally tunning both
the Fermi energy in graphene and the dielectric function of the environment, a
situation with no parallel in ship wakes.
  Using EEL we propose a source of graphene plasmons, based on a graphene drum
built in a metallic waveguide and activated by an electron beam created by the
tip of an electronic microscope.
  We also introduce the notion of a plasmonic billiard.
