Reading a thread over at SDMB about Trump and his habit of using pause+not! to cuttingly reverse the sense of a sentence. Some saw this as a revival of the usage, which had declined somewhat since its heyday in the late 80s/90s and I guess that’s true. At least I don’t see it or hear it as much but then of course I don’t frequent Twitter or FB so I could be wrong.
OED has an entry (not, adv, n., and int. C) and it’s interesting to see that the usage goes back to the late 19th century. I also see that OED comments that it was perhaps influenced by nit, adv., a word that is new to me. Here’s the entry for the latter term.
Etymology: Probably either < Dutch niet or < German regional (southern) nit not
U.S. colloq. Now rare.
= not adv. Also, in response to a question, etc.: = no adv.2 (sometimes used to indicate emphatic denial).Freq. used humorously or ironically following a statement to indicate that it should not be believed or taken seriously. Cf. not int.
1894 S. Crane in Press (N.Y.) 9 Dec. iii. 2/1 As he glowered at the little Cuban, he ended his oration with one eloquent word, ‘Nit!’
1895 W. C. Gore in Inlander Nov. 63 Nit.., not; sometimes an emphatic not.
1896 G. Ade Artie vii. 65 ‘He’s a nice boy,’ said he, and he added, after a deep sigh, ‘Nit—not.’
1903 W. M. Bickley Slang Dict. 10 ‘Is your scheme dead?’ ‘Nit; it’s a bird.’
1911 Our Navy (U.S.) Jan. 28 Assuming that you were stationed at the Naval Station, Cavite, P.I., where the heat is always close to the 100 mark, a stiff collared jacket and a heavy pair of woolen trousers would be nice and comfortable. Nit.
1942 Life 5 Jan. 57 A fine bunch of statesmen they got in this town—nit.
I think that perhaps in the OED comment on not, C certainly rates a promotion to probably, the usages are identical.