I am sure this has been spoken about before. I just cannot find it in the searches I performed. I am new to adwords, but I think this could work well to give your competition a good punch in the stomach (the good old BH way). Can't you get an IP switcher such as HideMyIP and simply keep on clicking their ads? From my limited adwords intelligence, it would cost them loads of money for the useless clicks and maybe even stop them from advertising on that KW. What do you think?