Mel 'n' Jack

I'm just watching a very old episode of Jack Benny's TV program and here's the joke they just did.  There's a cab driver played by Mel Blanc and he introduces himself to Mr. Benny by saying…

CAB DRIVER

I'm Harry Gilmore.  You and me went to Waukegan High School.  Don't you remember?  I was the one voted "Most likely to succeed."  Got my own cab.

JACK BENNY

Oh well, isn't that nice?

CAB DRIVER

Hey, what are you doing now?

JACK BENNY

I'm the voice of Bugs Bunny.

I'm not sure I quite understand the joke — an apparent ad-lib — but everyone (including Blanc) broke up.  The audience not only recognized Mel in the role but knew who he was.  Very nice.