From a Washington Irving character, it's a nickname for a New Yorker, Dutch-descended or otherwise
... have had 
experience in the unraveling of the origins of Dutch names have given to this 
matter... [DOC] [TLE] Start Reading - Penguin [PAR] Washington Irving is often tarred with this well-meaning brush, despite the fact ... 
Irving's best-known characters have themselves become household names: Rip 
.... for New York, recounting the history of its Dutch colonial forefathers, and in so 
... New Yorker: patrician, certainly, possibly of Dutch descent; a civic leader and... [DOC] [TLE] New York Rediscovered | Intriguing Stories from the History of New ... [PAR] We live in the midst of New York stories, and create new ones every day.