  Following a review of quantum-classical hybrid dynamics, we discuss the
ensuing proliferation of observables and relate it to measurements of
(would-be) quantum mechanical degrees of freedom performed by (would-be)
classical ones (if they were separable). -- Hybrids consist in coupled
classical ("CL") and quantum mechanical ("QM") objects. Numerous consistency
requirements for their description have been discussed and are fulfilled here.
We summarize a representation of quantum mechanics in terms of classical
analytical mechanics which is naturally extended to QM-CL hybrids. This
framework allows for superposition, separable, and entangled states originating
in the QM sector, admits experimenter's "Free Will", and is local and
non-signalling. -- Presently, we study the set of hybrid observables, which is
larger than the Cartesian product of QM and CL observables of its components;
yet it is smaller than a corresponding product of all-classical observables.
Thus, quantumness and classicality infect each other.
