It'll be the rap event of 1984 for Washington: Run DMC, Whodini, Newcleus, Kurtis Blow and the Fat Boys, all at the Washington Coliseum next Saturday, along with five break teams. The easiest to spot should be the Fat Boys, three guys weighing in at a total of more than 700 pounds. The sound will help, too: Darren Robinson, 17, is known as the Human Beat Box for his uncanny ability to evoke the percussive sounds that power all rap.

The other Fat Boys are Mark (Prince Markie Dee) Morales, 16, and Damon (Rock-Ski) Wimbley, and they're all from Brooklyn. "We were just street rappers," says Morales. "We all lived in the same block, and we'd rap on the corners for fun. We'd do talent shows around the community, and in schools, and then we won a rap contest at Radio City Music Hall."

Originally known as the Disco 3, they changed their names after their single "Fat Boys" became a No. 1 hit in New York. Their most recent hit is "Jailhouse Rap," which has them thrown in jail for eating too much.

Fatness is not a hook for most rappers, but the Boys say it's what keeps them "fresh." "I mean, we have the Human Beat Box and the way we run, we don't talk about how good we are, but how fun we are," says Morales. "We don't think of ourselves as hard rappers, but as comedians; that's a lot different."

"Jailhouse Rap" will be featured on the sound track for a new film from Leon Isaac Kennedy, "Cries of the City," due out early next year. It features Kennedy, Sammy Davis Jr., Millie Jackson and Kurtis Blow (the Fat Boys' producer). According to Morales, "it's about gang wars in Miami. This gang gets arrested, and we are members of another gang, and when they go to jail, we're in there with them. Their leader starts scatting and the Human Beat Box starts rockin', we start rappin', and there's a battle."

All three Fat Boys are still in high school, so they travel with tutors. "When the tour's over, we have to back to regular school," Morales sighs.