I can't understand you when you 'mumble'.
He 'mumbled' something and then left.
He 'mumbled' “Goodbye” and then left.
(..) You got any of those free doughnuts you use to soften people up? By the Service Department. All right, remember, no rustproofing. Commit to nothing. If you have to speak, mumble. -Au revoir, Le George. -Don't think it can't happen. Puddy, this is a pretty good move for you. -No more grease monkey. (..)1998 TvShow: Seinfeld Title: The Dealership Season: 9 Episode 11