A classy name given to someone who is (or is being) a complete idiot.
Fred's just a fudgenutter. Ignore him and hopefully he'll go away.
Instead of saying "fucker" saying "fudgenutter"
Joe: Jeez, That girl over there is such a preppy fudgenutter.
Jack: I know what you mean.
A name given to a 6th grader who is either stupid or can refer to 6th graders in general.
Noah: Look at these little fudgenutters, all dressed up.
James: dayum