The president of Comedy Central is portrayed as a high-power executive -- hip, shrewd . . . and a clown -- in new spots for the cable home of "South Park" and other comedic fare. The 15 ads, featuring fictitious network President Larry Shanet, represent the first Comedy Central project handled by Dweck & Campbell, New York. Copywriters/art directors: Lori Campbell, Steve Pearson, Scott Vitrone.