  GG Carinae is a binary whose primary component is a B[e] supergiant. Using
photometric data from TESS, ASAS, OMC, and ASAS-SN, and spectroscopic data from
the Global Jet Watch to study visible He\,I, Fe\,II and Si\,II emission lines,
we investigate the short-period variations which are exhibited in GG Car. We
find a hitherto neglected periodicity of $1.583156\pm0.0002$\,days that is
present in both its photometry and the radial velocities of its emission lines,
alongside variability at the well-established $\sim$31-day orbital period. We
find that the amplitudes of the shorter-period variations in both photometry
and some of the emission lines are modulated by the orbital phase of the
binary, such that the short-period variations have largest amplitudes when the
binary is at periastron. There are no significant changes in the phases of the
short-period variations over the orbital period. We investigate potential
causes of the 1.583-day variability, and find that the observed period agrees
well with the expected period of the $l=2$ f-mode of the primary given its mass
and radius. We propose that the primary is periodically pulled out of
hydrostatic equilibrium by the quadrupolar tidal forces when the components are
near periastron in the binary's eccentric orbit ($e=0.5$) and the primary
almost fills its Roche lobe. This causes an oscillation at the $l=2$ f-mode
frequency which is damped as the distance between the components increases.
