In Ohio, when you have been convicted of DUI and manage to keep your driving privileges, a judge can order a bright yellow license plate with red lettering (as opposed to our regular colorings). Perhaps that was the “temporary” drivers reasoning. However, is that an untapped keg in the bed?
More importantly, these plates don’t just mean you have too many DUIs. They mean you are on limited driving privileges because of DUI. People with those plates are generally allowed to drive only to and from their jobs. That’s why the person driving would put up a sign saying it’s not his truck–he thinks that will keep him from getting pulled over for violating limited driving privileges. It won’t, of course. That sign would actually make the cops more likely to pull you over because it calls attention to the fact that you have DUI plates.