Kind of like being at a concert. You paid your money and deserved to be able to enjoy the show. I don't think it is out of line to ask politely to quiet down please so you can hear and focus on the game. That is not a bad example for your son who will hopefully learn that it is alright to politely ask for needs to be met. If they respond poorly then your choices are more limited. Move away for a time....get help from an usher..talk to your son about the noise and see if he is doing okay. I think we are all annoyed by rudeness.