I used to own a Toyota Diesel pickup (loved that truck) and one of my former hobbies was making neon "art". I made a "YO" sign for the middle of the white lettering on the tailgate I could turn on with a switch in the cab. Not particularly for tailgaters but it did encourage them to back off if I turned it on. It was a good natured way of letting folks know I was aware they were close. Got a few smiles and waves along the way.
My three favorite things are the Oxford comma, irony and missed opportunities
The problem with humanity is: we have paleolithic emotions; medieval institutions; and God-like technology. Edward O. Wilson