Green’s Dictionary of Slang

(orig. US) used at the end of a declaratory sentence to reverse everything that has gone before, e.g. the Home Secretary is a liberal, tolerant and sophisticated person – not!

1899–1900		C.L. Cullen Tales of the Ex-Tanks 254: It was consoling to think that maybe he’d sue the railroad and get $50,000 or $100,000 damages out of it — not.
1902		‘Hugh McHugh’ Back to the Woods 99: I felt sure he’d be tickled to a stand-still-not!
1911		G. Bronson-Howard Enemy to Society 211: I guess he’d a fell for it — not!
1911		S. Ford Torchy 168: And you should have heard the talk [...] about the awful things they did at prep school [...] Almost made your blood run cold—not.
1921		N. Putnam West Broadway 72: ‘Well, did you get a chauffeur!’ I says gayly [...] ‘Yes, I did — not!’ says Jim.
1922		M.E. Smith Adventures of a Boomer Op. 46: Well, Hiram, we got that job — not.
1930		Robison Etta Kett 6 Jan. [synd. cartoon] So you’re going away? Oh, how I’ll miss you not?
1949		E.E ‘Doc’ Smith Skylark of Valeron 134: ‘See?’ ‘Uh-huh! Clear and lucid to the point of limpidity - not’.
1989		P. Munro Sl. U. 139: Not! No! You’ve got to be kidding!
1991		M. Myers et al. Wayne’s World [film script] Wayne: I love the suburbs . . . not!
2001		B. Bailey Dirty Mr Clean 🌐 ‘Great, Jennifer, that’s great.’ ‘Say good bye, Blair. I have to get busy on the phone to get your clean-up crews on the way.’ ‘Bye, Jenn. I can hardly wait.’ Not!
2010		C. Hiaasen Star Island (2011) 64: ‘You look whipped,’ he said. ‘Thanks. You look like Jake Gyllenhaal. Not’.
2022		J. Hannaham Didn’t Nobody Give a Shit 41: [A]ll them job interviews that’s gon just fall in my lap. Not.