Well, perhaps not a dark and stormy night, but a dull, windy and wet winter Saturday afternoon.
I was playing Doom on my 486, with headphones on on said dull afternoon. I had been playing a while and was really into it - Doom actually has great atmosphere with the music and the sounds of the various creatures and monsters shuffling around the map, and especially good atmosphere when played in a dimly lit room with proper headphones that cover the ears.
So my friend who I lived with at the time comes back from wherever he'd gone for the afternoon. In this place we rented there had been left these bean bag things for propping open doors. My back was to the door, and my friend seeing me fully engrossed in the game picks up one of these small bean bag frogs and throws it at me. The bean bag landed on my shoulder at the EXACT MOMENT one of those demons that go "Whoooooooooooo!!!!" (the ones that fire rockets) appeared behind me on the same side as the shoulder on which the bean bag had landed...
I almost died of heart failure right there on the spot. I certainly screamed like a little girl.