Beware the ninja.
EDIT: I just wanted to note that I didn't do this to be mean...I fully agree that it's wrong to steal anything, regardless of the reason...but I was bored and the thought of "WHY would someone steal a boulder..? Is it just... 'Oh..look...I think I'll steal a boulder today.'? The thought amused me, is all. I'm not trying to make fun of her...just the inherent humor in such a random thing being taken.