  We propose a new type of repeating transient outburst initiated by a neutron
star (NS) entering the envelope of an evolved massive star, accreting envelope
material and subsequently launching jets which interact with their
surroundings. This interaction is the result of either a rapid expansion of the
primary star due to an instability in its core near the end of its nuclear
evolution, or due to a dynamical process which rapidly brings the NS into the
primary star. The ejecta can reach velocities of 10,000 km/s despite not being
a supernova, and might explain such velocities in the 2011 outburst of the
luminous blue variable progenitor of SN 2009ip. The typical transient duration
and kinetic energy are weeks to months, and up to approximately 1 foe,
respectively. The interaction of a NS with a giant envelope might be a phase in
the evolution of the progenitors of most NS-NS binary systems that later
undergo a merger event. If the NS spirals in all the way to the core of the
primary star and brings about its complete disruption we term this a `common
envelope jets supernova' (CEJSN), which is a possible explanation for the
peculiar supernova iPTF14hls. For a limited interaction of the NS with the
envelope we get a less luminous transient, which we term a CEJSN impostor.
