I think my response to the first 'racist bigot' charge was probably the best and most effective one:
Them: "Well, you're just a racist bigot Republican."
Me:"And you can go f**k yourself. That accusation has no merit."
Tell me you haven't wanted to respond in the same way, somewhere along the line. We should have given in to that instinct to call them out on it. Notice how the Left is only interested in 'civility' when Conservatives get riled, while all the while their Liberal heros are blasting us? (see Bill Maher, Whoopi, Rosie O, Ed Schultz, Nancy P)