CJD is right, its not worth it…..giving any intelligent response of the kind to ignorant people doesn’t make a difference. It will just anger them more, I suggest you take the enemy by surprise and humiliate them with a semi-respectable reply. How about starting with….. “ ANNNDD A HAPPY BIRTHDAY TO YOU TO!!!” then go on saying random things, if he is only fairly ignorant and stupid, he’ll know you’re mocking him and don’t care a toss. On the other hand he may think you’re a nutter and leave you alone. Both ways, will probably rid the fool from causing you any trouble.