To answer my own question: 'The word doodle first appeared in the early 17th century to mean a fool or simpleton. It may derive from the German Dudeltopf or Dudeldop, meaning simpleton or noodle (literally "nightcap").' [1]
Not sure why the author of this article couldn't be bothered to complete the etymology he started.
Not sure why the author of this article couldn't be bothered to complete the etymology he started.
[1] http://en.wikipedia.org/wiki/Doodle