My husband is the same way - he smiles and waves when someone flips him off. I don't have the restraint to "kill them with kindness."
I have been surprised at how many moms have been willing to flip someone off in front of their kids--this is not in reference to you. I am not one who initiates things, I do respond sometimes. But there are times when the person is being pretty stupid and I don't want to be caught acting the same way--though that logic doesn't always work for me:).
I believe it's been pulled.