Only once that I can remember. I was about 8 years old and bending over the side of my bed to grab something from under it, and I went too far off the edge and fell over backwards. It was not pleasant. -_-
No. But that's only because I've never been "in" a bed. I have, however, been ON a bed and, allegedly, fell off said bed. However, I still maintain that the cat pushed me off (and I have filed an appeal stating so).
While the physics of the situation would tend to be probative to find the cat innocent; I have personal knowledge of the surreptitious powers of the common house cat, and I am sure you will win your appeal.