What was Lefty, the letter salesman, selling? (Soundbite of TV series, Sesame Street) Mr. FRANK OZ (Actor): (As Lefty) And would you like to buy an O, round and neat, a nearly but circle ...

When Sesame Street debuted 50 years ... (SOUNDBITE OF SONG, "C IS FOR COOKIE") OZ: (As Cookie Monster, singing) Now, what starts with the letter C? Cookie starts with C. Let's think of other ...