Green’s Dictionary of Slang

1. to accost truculently; to reprimand.

1902		1902 Hull Dly Mail (Yorks) 18 Nov. 4/5: Of course, there are the usual few who have been ‘spragged’ by the employers [...] for insobriety and other offences.
1914		C.J. Dennis ‘The Play’ in Bulletin (Sydney) 16 July 47/1: A tug named Tyball (cousin to the skirt) / Sprags ’em an’ makes a start to sling off dirt.
1935		‘L. Luard’ Conquering Seas 41: ’Twas only to save you from getting spragged .

2. to persuade.

1916		C.J. Dennis ‘To the Boys Who Took the Count’ in Moods of Ginger Mick 101: But ’ere’s to the coot wiv the ’ang-over thirst / ’Oo sprags a stray toff fer a loan.
1918		C.J. Dennis ‘Half A Man’ in Chisholm (1951) 104: ’Er game’s to see the girl at this address / An’ sprag ’er in regard to comm’ down / To take Smith be su’prise.

3. (Aus./US) to meddle in someone’s plans, to thwart.

1938		X. Herbert Capricornia (1939) 289: Hello Barney — spragged well and truly, eh?
1938		Dly Courier (Connelsville, PA) 24 Feb. 9/7: Grand jurors [...] effectively spragged State Motor Police in their war on thenumbers racket.
1941		Birmingham Dly Gaz. 26 Aug. 1/3: [headline] Hitler’s Spring-Board Badly Spragged. No Jump Off for India.
1946		Republican & Herald (Pottsville, PA) 25 May 6/6: Lost Creek hammered the Lutherans [...] and the Methodists spragged the Reformeds by 10-5 [...] in Sunday School softball.
1953		Wilkes-Barre Times Leader (PA) 21 Jan. 14/2: Senator Morse [...] spragged Senate confirmation of eight cabinet choices.

4. (UK juv., also spragg) to inform on another pupil; also as n., to tell tales.

1996		J. Baker Death Minus Zero (1998) 47: ‘We won’t spragg you,’ said the little blond one.
2001		OnLine Dict. of Playground Sl. 🌐 sprag v. & n. to alert a teacher or ‘grown up’ of a misdemeanor a ‘tell-tale’ or liar.