I remember once trying to explain car bumper sticker culture to some relatives who aren’t American and they looked at me like I had two heads. Understandable because it doesn’t make sense to me either but you really can glean a bizarre amount of info on a person from the bumper stickers on their car. Often times that info is “my politics are this flavor of incoherent and I’m VERY annoying about it to all of my friends and family.”