What goes in the "What do you have to say?" box
Great Question! Your entry should contain text that is relevant to the license plate. For example you might indicate the type of vehicle, the location, the owner.
Why? Because these are the words that search engines will use to determine the content of your page. Also, Google will place ads that are relevant to your text. For example: Text that says "I saw this Porsche 911 outside of the Park Plaza Hotel in New York City" might show ads for Porsche Dealerships or The Park Plaza Hotel.