Wow ... not sure how safe this would be, but this is a cool idea!
This is a programmable LED license plate frame that you can program with several different 'sayings'. You can let everyone know that your favorite team won, what school you went to, or ~anything~ else you might be interested in saying. You have a remote control to change what it says. You can also chose to have it on all the time or only when you step on the brake. You do have to wire it, with two wires, into your cars system. Great way to let people know that they aren't driving too well too!