Green’s Dictionary of Slang

(US) an irritable mood, a ‘state’.

1890		Vermont Jrnl (Windsor, VT) 14 June 4/4: ‘You didn’t bring Lottie and Bess?’ ‘Well, no, I didn’t [...] Came off in such a swivet’.
a.1905		in J. Wright Eng. Dial. Dict. V 893/2: What a swivit ee’s in.
1915		Watuga Democrat (Boone, NC) 27 May 1/1: It is curious that a disinterested man like Gardner should get in a swivet over it.
1932		Brooklyn Citizen (NY) 14 Dec. 11/3: So long as books are being published there can be no reason why anyone should get ina swivet about Christmas presents.
1938		M.K. Rawlings Yearling 265: Don’t git in a swivet, boy.
1940		Selma Times-Jrnl (AL) 23 June 3/1: [advert] Don’t Fuss and Fume! — it only makes it hotter to get in a swivet over the weather.
1952		Rutland Dly Herald (VT) 10 Mar. 9/7: You can’t get yourself in a swivet over some isolated instances if mild abuse.
1966		H.S. Thompson Hell’s Angels (1967) 154: The locals had had nearly a week to work themselves into a swivet.
1978		Palm Beach Post (FL) 8 May 8/2: My liver has spoken. It was obviously in a swivet over the gentle yet firm years of loving douse that I had contrived for it.
1985		J. Briskin Too Much Too Soon (1986) 356: ‘In a hot swivet,’ Alexander said.
1990		Star Democrat (Easton, MD) 23 Nov. n.p.: Anyone who is faced with the same treatment don’t get into a swivet.
1999		Guardian Guide 15–21 May 10: The hypothetical bloke from Tumbridge Wells who was thrown into a swivet by the drama’s non-stop rumpo.
2004		Palm Beach Post (FL) 1 Jan. 12/2: Why get Kankakee, Ill. in a swivet if it’s Houston that the evil-doers are gunning for?