Jeff Hoffman has gone and taught me to open my big mouth.

Over the summer, I wrote that the time had come for a new District of Columbia license plate. America's 200th birthday was five years ago and counting, I noted. But our streets -- and eyeballs -- are still infested with plates that read "Bicentennial" and "1976."

Jeff is editor of City Hall New Times, a newspaper published by the District government, and unlike most journalists, he must have a good filing system. He called the other day to ask/dare me to serve on a committee chaired by Mayor Marion Barry that will choose a new city tag. Having been taught to put my money where my mouth is, once I'd opened the latter, I accepted.

But here's the catch. The committee will not choose from among the renderings or sketches of professionals. The only participants in the new-tag derby will be the public. All of you, D.C. residents or not, are invited to submit a design for a new D.C. license plate.

"Design" means not just an artist's sketch and not just a slogan, but a combination of the two. Your concept must be big enough to accommodate six numbers or letters. Otherwise, there are no requirements or restrictions.

First prize: a special citizen merit award, a reception in your honor at which the mayor will unveil the winning design and free auto registration for one year. Additional prize: an interview with yours truly, published in this space.

Please, no White House porticos or Capitol domes. The whole idea is to come up with artwork and a slogan that captures Washington as a city, not as the seat of the national government. "We feel that local identity is sometimes lost in the shadow of the federal presence," says Jeff Hoffman, in one of the great understatements of our time.

According to Jeff, the winning entry could be adopted as the city's official license plate by early next year. The contest deadline has not been firmly set, although it will probably fall around Dec. 15. All designs should be sent to City Hall New Times, Office of Communications, Room 219, District Building, Washington, D.C., 20004