Stickers on cars has been a hard no for me for years. Just an advertisement for how much of an idiot you are 99% of the time. Saw two pro gun ones recently that stood out. The first said something like "If you believe that guns kill people, then pencils misspell words and cheeseburgers make people fat". Pure idiot garbage.
The second had an icon of a handgun and said "nothing in this car is worth losing your life over" to which I really wanted to write a note saying "You're 2011 ford escape isn't worth taking someones life over, you fucking loser." and leave it on their windshield.
Still remember one from years ago on some rusted out truck that said "Built with tools, not chopsticks." American cars are fucking overpriced garbage and have been for years.