Merging black holes radiate enormous amounts of energy - several solar masses worth! Unlike most astrophysical happenings, this happens on very human timescales. Most of the energy is released in the order of a second at frequencies of 1 to 1000 Hz. Humans are very much designed to sense and react to disturbances at such scales.
Fortunately or unfortunately the radiated gravitational waves are minuscule (fractional distortions of ~$10^{-20}$) when they reach Earth and require exquisitely sensitive devices to detect them. I suppose it is totally implausible to experience a 1% gravitational wave, but presumably that would be something that an isolated person could clearly feel and hear. Would the person be injured or destroyed? Standing on the surface of the Earth, I assume one could see and hear the effect much smaller waves (~$10^{-4}?$) in the environment. Would such a wave dissipate enough energy in the Earth to effectively destroy it? The most general phrasing of the question is to ask: what effect would high-intensity gravitational waves have on solid matter and biological systems?
[Of course this all assumes some relatively-local but benign source of gravitational waves - such that we that we wouldn't all instantly be fried by a burst of gamma rays or suchlike.]
