  In general relativity producing a regular bounce entails violation of Null
Energy Condition for a dynamical source in the model. That generically
indicates existence of ghosts or other instabilities. However, in cuscuton
modification of gravity, the correspondence between a background bounce and
violation of Null Energy Condition for dynamical sources is broken. Cuscuton is
an Infra Red modification and it can make the background go through a regular
bounce. At the same time, since it does not contain any dynamical degrees of
freedom, it does not lead to ghosts or other instabilities. Here, we present a
toy scenario of a regular bouncing cosmology and prove this claim. Our model is
presented as a proof of concept at this point and does not aim to explain
observations in late time cosmology.
