Waking up to the feeling of being grabbed by the shoulders and urgently shaken when I was the only person at home was a rather odd experience.
Oh, and being woken up by the sound of lighting striking just outside my window fucking sucked too. Additionally so because it was five in the fucking morning. It's always nice to start the day by being jolted awake by a deafening thunderclap and almost falling out of bed.
Edit: Actually, come to think of it, I remember one that was much worse than either of the other two:
Waking up with terrible stomach cramps, somehow managing to stumble into the bathroom and throw up, only to collapse on the floor, screaming and sobbing in pain for some half an hour. I must've completely forced that one out of my memory. Man, that sucked...