Mel Blanc [wiki], nicknamed "The Man of a Thousand Voices" for good reasons, was the world's most gifted voice actor. Here's a video clip of an interview by David Letterman in 1981, where Mel explained how he got the inspiration to do voices for cartoon characters like Bugs Bunny, Porky Pig, Yosemite Sam and so on.
Hit play or go to Link [YouTube] - Thanks Algonkin!
http://www.videosift.com/video/Mel-Blanc-Bugs-Bunny-and-other-Looney-voices-Tonight-Show
was there video of the rest of that show? letterman said he had hunter s. thompson on there after mel blanc! now what a character HE was... would have been cool to see that interview.
I can only imagine Carson might have done a better job of responding to Blanc's amazing vocal demonstrations by engaging him more and getting something more spontaneous out of him. Did Carson have Blanc on his show?