http://www.straightdope.com/classics/a3_132.html
It’s a tiny little town (pretty much an intersection with some houses) near where I grew up. The USPS doesn’t recognize it as a town, because you have to have a certain volume of mail coming in for them to grant you your own zip code. I believe they rely on the Turmansburg NY post office & zip code.
This may not make it seem terribly real to the outside world, but people there do refer to themselves as living in Podunk NY, as the residents of nearby Perry City do. Neither are incorporated because they’re too small, but they still exist.
There’s even a backpacker’s hostel in Podunk.