What happens when you send too much international traffic? will they still pay out for that month or will they take my money?
They will first deduct all international clicks (but still count the impressions). Thus, you will not only lose the money from the international clicks, but the per click will be lower for all US based clicks. Then, they will probably kick you out of the program because it is against the rules to have too much international traffic. Further, it will take them up to 3 months for you to get your check. So the best thing to do is use Geo-Targeting.