Green’s Dictionary of Slang

1. (US prison) the electric chair.

1971		(con. 1940s) J. Brown Monkey Off My Back (1972) 81: I was next door to ‘Old Sparky’.
1971–2		C. Shafer ‘Catheads [...] and Cho-Cho Sticks’ in Abernethy Bounty of Texas (1990) 215: Sparkie, n. – the electric chair.
1989		J. Morton Lowspeak 107: Ol’ Sparkey – nickname for the electric chair in Florida. When the mass murderer Ted Bundy was executed in January 1989 part of the waiting crowd sang ‘On top of ol’ Sparkey’.
1996		S. Earle ‘Ellis Unit One’ 🎵 Folks just got too civilized, Sparky’s gatherin’ dust.
1999		Indep. 20 July 15: State authorities are to review the use of ‘Old Sparky’, as the electric chair is known.
2001		(con. 1981) A. Wheatle East of Acre Lane 147: De beast would reintroduce de sparky chair, dread. Your backside will fry like egg.
2007		C. Goffard Snitch Jacket 99: I get Old Sparky if I put a bullet into him.

2. a machine that dispenses electro-convulsive therapy (ECT).

2012

D. O’Donnell Locked Ward (2013) 89: Wayne had five or six blasts of ECT. I was there the first time he was hookked up to Old Sparky.