  Using hydrodynamical numerical simulations we show that high-velocity ejecta
with 10,000 km/s in the outbursts of the supernova impostor SN 2009ip and
similar luminous blue variable (LBV) stars can be explained by the interaction
of fast jets, having velocity of 2000-3000 km/s, with a circumbinary shell
(extended envelope). The density profile in the shell is very steep such that
the shock wave, that is excited by the jets' interaction with the shell,
accelerates to high velocities as it propagates outward. The amount of very
fast ejecta is small, but sufficient to account for some absorption lines. Such
an extended envelope can be formed from the binary interaction and/or the
unstable phase of the LBV primary star. The jets themselves are launched by the
more compact secondary star near periastron passages.
