I was driving somewhere one afternoon, was really tired and dozed off. 'Someone' yelled at me, nothing really intelligible, just a loud, weird "hey" that startled me awake just before I was to drift off the side of the road. I remember looking all around; there were no other vehicles, no people on the side of the road, no one who could have made the noise. The radio in the car was off and the car itself was in good working order. I had never heard a noise like that before nor have I heard it since. I am utterly convinced it was a 'guardian angel'.