Mr Angry said:
Check your rule book dude, if no shot is offered, it is irrelevent where it pitches.
Just to clear this up. The ball can pitch anywhere from leg-stump to wide on the offside.
The law you're thinking of is where the ball hits the batsman - this is called the point of interception. If the ball bounces outside off, and hits the batsman in front of the stumps, he can be given out regardless (if the umpire is satisfied that it was hitting the stumps)
If the ball bounces outside off and hits the batsman outside the line of the stumps, he can only be out if he doesn't play a shot - if he does play a shot, even if it was going to wreck the stumps completely, he cannot be given out.
So: It is where the batsman is hit, not where the ball pitches, that you're thinking of regarding playing or not playing a shot.