  There is growing evidence for high-frequency gravitational waves (HFGWs)
ranging from MHz to GHz. Several HFGW detectors have been operating for over a
decade, and two GHz events have been reported recently. However, a confirmed
detection might take a decade. This essay argues that unexplained observed
astrophysical phenomena, like Fast Radio Bursts (FRBs), might provide indirect
evidence for HFGWs. In particular, using the Gertsenshtein-Zel$'$dovich effect,
we show that our model can explain three key features of FRBs: generate
peak-flux up to $1000~{\rm Jy}$, naturally explain the pulse width and the
coherent nature of FRBs. In short, our model offers a novel perspective on the
indirection detection of HFGWs beyond current detection capabilities. Thus,
transient events like FRBs are a rich source for multi-messenger astronomy.
