Comedy is king on ''Sponk!,'' a new game show whose premiere episode will be shown on Nickelodeon this morning at 7:30. A weekly series on Noggin (Time Warner Channel 129) at 9:30 Monday nights, ''Sponk!,'' features two teams competing in improvisational games. Above, Johnathon McClain, the show's host, is surrounded by team members (clockwise from top left, Julia Melanie Kay, Vanessa Lengies, Tim Dorsch, Lori Wells, Scott Irby-Ranniar, Miles Thompson, Louie Torrellas and Allie Berbedes). Viewers can suggest topics for skits via the Internet. (www.nick.com or www.noggin.com).