This one is the underlying "Naval Jack" with the red stripes, rattler, and "DONT TREAD ON ME." (The server is spotty and X's out once in a while.) NAVAL JACK
I would recommend using the spelling DON'T, because the sheeple in the car behind you is just going to think, "Those gun nuts can't even spell" if you copy it with the historically correct DONT.
You might want to try it with THE SECOND AMENDMENT across the top, and alternatively with THE RIGHT TO KEEP AND BEAR ARMS.
Another option is:
DEFEND THE RIGHT TO KEEP AND BEAR ARMS across the top,
DON'T TREAD ON THE SECOND AMENDMENT across the bottom.
