Ball hits bat

[rbmartin]

If you're playing in OBR :
6.05 (h) A batter is out when after hitting or bunting a fair ball, his bat hits the ball a second time in fair territory. The ball is dead and no runners may advance. If the batter runner drops his bat and the ball rolls against the bat in fair territory and, in the umpire's judgment, there was no intention to interfere with the course of the ball, the ball is alive and in play...

So you need to ask this question: Did the bat hit the ball or did the ball hit the bat. This may sound silly but that's the way you have to look at it.
A smart hitter will disgard his bat into foul territory so there's nothing to chance.