Ok, I get it. People feel the need to tell everyone how cool they are by inferring that they participate in a certain activity.
We've got people up here that have a "Roots" sticker, in the shape of the state, on their back window. Gotta let everybody know you were born here. Saw the same thing in Colorado back in the early 80's with the "Native" stickers.
Similar to the Browning sticker on every single truck in central Texas...