  A solid object impacting on liquid creates a liquid jet due to the collapse
of the impact cavity. Using visualization experiments with smoke particles and
multiscale simulations we show that in addition a high-speed air-jet is pushed
out of the cavity. Despite an impact velocity of only 1 m/s, this air-jet
attains \emph{supersonic} speeds already when the cavity is slightly larger
than 1 mm in diameter. The structure of the air flow resembles closely that of
compressible flow through a nozzle -- with the key difference that here the
"nozzle" is a \emph{liquid} cavity shrinking rapidly in time.
