SRS, there ought to be a check-box to tell the 'do you want to accept a cookie' prompt you answer 'yes' every time. You click it once, and for future cookie-bestowing attempts from the same exact bestower, it will just decline without asking.

The down side is, if you accidentily permanently decline one you want, you have to go into permissions, a bit harder to find, and tell it that address is OK.