Twenty years ago, the Sugar Hill Gang helped usher in the hip-hop age with the single "Rapper's Delight." Now the group is doing its part to expose hip-hop to the youngest generation.In April, the group released "Jump On It," a children's album containing tunes such as "Jump On It," "Kick A Rhyme With Dr. Seuss," "ABC's" and "Kids' Rapper's Delight (Kids' Rap-Along)" (see "Sugar Hill Gang, Grandmaster Melle Mel Send One Out For The Kids"). Next week the influential rap crew, along with the Boys & Girls Club Of America, will be sponsoring a double-dutch jump rope contest for children; the contest's music will be taken from the "Jump On It" disc. Winners will receive a CD or cassette copy of the album autographed by the Sugar Hill Gang members plus a package of various other goodies courtesy of Kid Rhino Records, the label that issued the LP. Every participant will receive a "Jump On It" t-shirt. The contest will take place at Boys & Girls Club Of America locations in New York, Houston, Detroit, Los Angeles and Atlanta on Friday, October 29 at 6:30. For information on the Boys & Girls Club nearest you, check out the organization's Web www.bgca.org, or call the organization's national headquarters at (404) 815-5700.