Haha just thought of a greeeeeaaat idea!
Actually I've played around with this for years in my mind and it's not a novel concept. It's just not used as often as it should be!
Let's use Hamtaro actually because he's the perfect, stereo-typically innocuous paragon of child-like exuberance that I'm looking for. Replace his voice with a much deeper voice such as the voice of the narrator for Forensic Files or, better yet, the voice on Law & Order that says, "In the criminal justice system.." (Blah blah blah Law & Order sucks!).
Can you feel it now? Keep all of Hammy Ham's lines the same and we've got some funny moments.