Who's throwing like a girl? Repeat after me...from the shoulder...from the shoulder. Just kidding about that. It's a creative idea, although I'd call it more of a proverb than a superstition. The crutches, I'm sure, are there for a reason, but they are distracting from the picture. Either ditch the crutches just for the shot, or get her to take the picture while you are throwing the rock (assuming it's not a self portrait).
Certainly meets the challenge and I like the composition, but it lacks punch. The crutches are also distracting, but I realize she may have been your only available model!
I think thats more of a saying than a superstition, the photo is good though. i liek the tone of blue in the sky, the crutches are distracting. not sure if they were part of your idea or just utilitarian.
Cute image, crutches a nice touch, but doesn't look like a house nor that she is living in it. But, don't think its an urband legend or a superstition just more of a advice fable kinda thing. But by itself, its a nice image.. maye move the model over a touch to the left to hide more of the door sign.