Hey, BDSM people and others do advertise their interests on their cars; you just don't recognize the bondage flag when you see it, just like my mom didn't know what the rainbow meant until I told her. One of my favorite cars in the apartment complex I used to live in (though I never met its owner) had a license plate indicating the owner had received a Purple Heart, and on either sides of the license plate rainbow and bondage flag stickers. (Someone had guts.)