  The second order correlation function is traditionally used to characterize
the photon statistics and to distinguish between classical and quantum states
of light. In this article we study a simple setup offering the possibility to
generate strong anti-bunched light. This is achieved by mixing on a beam
splitter a coherent state with a state with a non-negative Wigner function,
such as squeezed states or weak Schr\"odinger cat states. We elucidate the
interference mechanism generating such strong antibunching and relate it to
unconventionnal photon blockade. We also detail how this effect can be used to
measure weak squeezing.
