BOSTON–Struggling to find the perfect marketing hook for a new rainbow-colored string-cheese snack, Holland Mark Advertising executive Darius McLain got in touch with his own inner-child demographic–a purchasing sector he had all but forgotten since the onset of adolescence. "I asked myself, what would make a kid want to buy Color Magic Cheez-bows?" said McLain, 44, after the emotional breakthrough. "Only after looking within myself and rediscovering the 8- to 12-year-old male buried deep inside did I hit upon the ideal angle." McLain next plans to get in touch with his feminine-urban-professional side to develop a campaign for No Nonsense pantyhose.