Instead of just not giving them money, you can put a little something in their donation kettles that will hopefully have at least a tiny little impact and will perhaps make someone in their organization think. Instead of putting real money in their kettles, put in one or more of the following handy-dandy fake bills with a special message for the Sally Ann:
or

Just print copies out, cut them out, and keep them in your jacket pocket for those moments when you see a Sally Ann bell-ringer!