I imagine I would probably go irrevocably insane upon the simplest and briefest sight of the Great Old One himself. I would then grow some sort of unnatural appendage which I would use to tear peoples' livers/entrails out and eat them, only to realize far too late that I am actually not suddenly capable of digesting or surviving on human viscera and end up dying horribly.
Either that, or just shoot myself and everyone around me, because really. It's like the Reavers from Firefly. You really, really would rather be dead than be captured alive.