  We study effects of a rippling gravitational background on a scalar field
with a double well potential, focusing on the analogy with the well known
dynamics of the Kapitza's pendulum. The ripples are rendered as infinitesimal
but rapidly oscillating perturbations of the scale factor. We find that the
resulting dynamics crucially depends on a value of the parameter $\xi$ in the
$\xi \,R\, \phi^2$ vertex. For the time-dependent perturbations of a proper
form the resulting effective action is generally covariant, and at a high
enough frequency at $\xi<0$ and at $\xi>1/6$ the effective potential has a
single minimum at zero, thereby restoring spontaneously broken symmetry of the
ground state. On the other side, at $0<\xi< 1/6$ spontaneous symmetry breaking
emerges even when it is absent in the unperturbed case.
