Believe or not it was meant to be a serious question.
The
Compton wavelength λ is defined as;
λ = h/mc
where h is Planck's constant, m is the mass of the object and c is the speed of light.
The physical interpretation of this equation is to consider the shrinking of a macro sized object of mass m and at what size does the object behave quantum mechanically when colliding photons results in it scattering.
For the electron mass of 9.1 x 10⁻³¹ kg, the Compton wavelength is 2.43 x 10⁻¹² m.
Given the 'classical' radius of an electron is around 2.82 x 10⁻¹⁵ m, one would expect electrons to behave quantum mechanically.
A koala on the other hand of mass 1 kg has a Compton wavelength of 2.21 x 10⁻⁴² m.
So clearly macro sized koalas cannot behave quantum mechanically.