Awful situation! I once had someone do this under the rotor disc of an aircraft I was flying. The passenger was being closely supervised by experienced ground staff as he disembarked but he suddenly turned, walked back under the disc and raised his arms to wave goodbye. I immediately moved the cyclic away from him and the rotors thankfully missed his fingers, but only just. A pilot's nightmare, doesn't matter how much you brief some people, they still forget about basic self preservation.