  Rattling phonon modes are known to be origin of various anomalous physical
properties such as superconductivity, suppression of thermal conductivity,
enhancement of specific heat etc. By means of DFT+$U$ calculations we directly
show presence of the rattling mode in the quadruple perovskites
CuCu$_3$V$_4$O$_{12}$ and CuCu$_3$Fe$_2$Re$_2$O$_{12}$ and argue that this can
develop in others as well. It is demonstrated that Cu ions at $A$ sites vibrate
in the center of the icosahedral oxygen O$_{12}$ cages and the corresponding
potential has a complicated form with many local minima.
