Let me try something:
"I believe that on Friday, August 6, 2004, a member of this board, or someone known by a member of this board, will be in an unfortunate incident involving a car. So, please tell everyone you know to be careful tomorrow and be careful yourself."
Now, how can this "prediction" possibly go wrong? Given the large number of people who are members of this board and, further, the number of people known by members of this board, the odds against "an unfortunate incident involving a car" (a common event) are probably insignificant.
Still further, I didn't specify what incident would occur, only that it would involve a car and it would be unfortunate. That could range from stubbing your toe in a parking lot to having a major multi-car pile up. Heck, spilling your soda during an exciting car chase in a movie would work.
And if none of that happens to anyone in our massive pool of people, it's because I warned them in time?
Now, how do you distinguish my prediction (which I absolutely concocted solely from my own imagination) from something like Luci's premonition?