This happened to me recently. I was in the kitchen and decided, for whatever reason, to stretch. There was a drawer open a few feet away. I held the stretch for long enough to induce this blackout, and it went almost exactly as you describe. The next thing I remember is a ten second fade-in to awareness: I'm sideways on the floor making gibberish noises and holding the back of my head. The drawer, now above me, was knocked off its rails. As I reflexively got up from fainting, I did not have awareness of the open drawer, and bonked the back of my head on it.

It was an extremely interesting moment of observing conscious awareness that I think about all the time.