When you gotta polka, there is no waiting. And when 9 o'clock strikes at Blob's Park, the band gets going. Everybody has his polka style: scareen from one end of the floor to the other, or hop high and fast in one place, or sedately march around the edges, or strut and twirl around, flipping from side to side.

Blob's is dark on weeknights, but on Friday and Saturday nights and Sundays starting in the afternoon, the mirrored ball revolves in a ceiling sea of acoustical tiles like a lone marble on a playground, and the band flits from the "Bumpsy Daisy" to the "Tick Tock Polka" to the "College Park Cha Cha." The fancy steppers break the ice, but soon the up-to-a-thousand crowd packs the dance floor. The waitresses, between delivering pitchers of dark beer and platters of wursts, are the best dancers, wiggling so their lace bloomers show under their dirndls. A 78-year-old grandmother in spangles and velvet, who hasn't missed a polka in 12 years, no longer dances on the tables, but still drags out a young one for each number with, "Come on, you lazy bums."

Sequins and see-throughs. Pencil mustaches atop cuff-to-collar plaids. Piled-high red hair and cut-short, lime green skirts. Red gowns and gold shoes. Crew neck sweaters are creeping in, along with the new house drink -- pina colada. But so far not a single third shirt button is unbuttoned, and all the neck chains are on the women. More a Saturday night flush than a fever, the crowd is heavy into middle age, Polish and German, with sprinklings of high school youths in backless high heels, Latinos chewing gum and dancing with their coats on.

Five Happy Birthdays and an anniversary song later, the brass band slips "Hava Nagila" into a polka. Ethnic it is, but monolithic no longer. apter of the Ku Klux Klan" called WASH-AM radio newscaster Dick Uliano s