According to Advertising Age, not counting Sunday-night NFL games, the two most expensive shows on which to advertise on cable, in their respective categories, are Comedy Central's South Park ($45,000 per 30-second spot) and ESPN's postgame Sunday night SportsCenter ($33,000). Are there any common elements? Well, both feature a character named Kenny, originate from a hibernal backwater and aren't averse to violence. Each has a gurulike figure. South Park's is Chef. On SportsCenterbe's Dr. Jack Ramsay.