the Night Vale Harbor and Waterfront Recreation Area never really existed, and was in no way a multimillion-dollar failure of municipal planning.
Night Vale often uses negation as an implicature, similarly to use by government agencies of the Glomar response: “We can neither confirm nor deny the existence of the faceless old woman who lives in your home.” Listen to Radiolab‘s podcast episode on a Cold War use of the Glomar response here.
Older than you think—Not! Adding “not” at the very end of a sentence as a form of negation is not a new construction. An early OED citation is from George Eliot’s The Mill on the Floss (1860), in which she writes:
She would make a sweet, strange, troublesome, adorable wife to some man or other, but he would never have chosen her himself. Did she feel as he did? He hoped she did—not.
(More words and usages that are older than you think at this listicle at the Guardian UK.)
h/t Lexica @Metafilter