And if you can, pay with your purchase with $2 bills. (You can get them at your bank). This denomination is rarely used, and will get the attention of the Staff at Starbucks, AND the "2" is symbolic of our support for the 2nd Amendment.
Cash drawers full of $2 bills at the end of the day in every Starbucks in the country would get their attention that's for sure. If you owned a business, who would you listen to for setting policy--a bunch of loud, disruptive, ranting protesters trying to convince your customers to not patronize your shop, or a bunch of quiet, polite, law-abiding people who calmly came in to your shop, purchased your product, and went about their business?
Just sayin'...