Green’s Dictionary of Slang

1. (also fine Scot) an ill-tempered person, esp. one who is susceptible to teasing.

1812		Vaux Vocab. of the Flash Lang. in McLachlan (1964) 263: scot a person of irritable temper, who is easily put in a passion, which is often done by the company he is with, to create fun; such a one is declared to be a fine scot.
1823		‘Jon Bee’ Dict. of the Turf, the Ring, the Chase, etc. 155: Scot a butcher’s designation of a fractious man.
1824		Annals of Sporting 1 June 405: Madden [...] turned Scot, as our butchers term a mad-un.
1835		G. Kent Modern Flash Dict. 29: Scot – a savage person.
1848		Flash Dict. in Sinks of London Laid Open [as cit. 1835].

2. a bad temper, a fit of irritation.

1859		Hotten Dict. of Modern Sl. etc. 87: scot temper, or passion; ‘oh! what a SCOT he was in,’ i.e., what temper he showed.
1861		Bell’s Life in Sydney 20 Apr. 3/2: Moffy [...] was evidently at the moment in a great scot.
1873		Sl. Dict.
1880		‘Edward Howe’ Roughing It in Van Diemen’s Land 18: He’d do anything when he’s in a scot.
1895		C. Crowe Aus. Sl. Dict. 70: Scot, anger, passion, etc.
1904		‘Dads Wayback’ in Sun. Times (Sydney) 24 July. 1/3: ‘Dad’s in ther kitchen [...] he’s got ther flooenza, an ain’t hea in a scot, my word!’.
1910		Bulletin (Sydney) 6 Oct. 5: By-and-bye, the Editor he comes into the Art Department in a great scot and says: ‘Look ’ere; the printers is waitin’ for that front page. Where in – – is old Hop?’.