There are also stickers that communicate with the in crowd, without tipping off others. One of those AR bolt face stickers, or Molon Labe.
I have only 2 decals on the car. Rear windshield, lower left corner is an American flag. Lower right corner is this:
There is also a tasteful chrome cross on the trunk lid. Same size and general appearance as the manufacturer's logo, model name, and trim info.
God, guns, country and coffee. Keeps most of the aholes back.