Green’s Dictionary of Slang

a general term of address to a man or boy.

1838		J.C. Neal Charcoal Sketches (1865) 48: He therefore picked up Smalt, and placing him on his knee, remarked [...] ‘You’re a clever enough kind of a little feller, sonny’.
1858		‘A. Pendragon’ Queen of the South 20: Dang it, sonny, them’s nuthun’ like pasties mother made.
1869		H.B. Stowe Oldtown Folks 321: She stroked my head, and looked lovingly at me, and called me ‘Sonny’.
1871		E. Eggleston Hoosier School-Master (1892) 37: They’d pitch you out of doors, sonny, neck and heels, afore Christmas.
1889		B. Mitford Fire Trumpet II 144: ‘Say, sonny,’ remarked the cabman to the smart boy at the door.
1890		Sporting Times 1 Feb. 2/1: Hullo, sonnie, what have you done with the monkey and the organ?
1898		H. Macfall Wooings of Jezebel Pettyfer 13: ‘So git along, sonny, and play!’ she called.
1905		Sporting Times 18 Feb. 2/3: So come along, sonnie, and play the game.
1913		‘J.W.L.’ Slave Stories 66: Yes, sonny, me fit one time.
1916		J.N. Hall Kitchener’s Mob 59: Blimey, son!
1923		O. Onions Peace in Our Time 116: Don’t let that worry you, sonnie.
1925		K. Mullen ‘Westernisms’ in AS I:3 153: ‘Sister’ for any woman or girl, and ‘Son’ for any boy.
1930		M. Allingham Mystery Mile (1982) 346: ‘Hullo, Sonny Boy,’ he said, grinning.
1936		J. Curtis Gilt Kid 275: ‘You’ve got just two chances of that, son.’ ‘Yes, I get you. A dog’s chance and no chance at all.’.
1938		X. Herbert Capricornia (1939) 344: No Sonny. [...] There aint no need for this here railway at all.
1942		Whizzbang Comics 45: Why, of course I don’t want to, sonny!
1948		(con. 1944) N. Mailer Naked and Dead 233: You do that, son, and you and me won’t have no trouble.
1957		G. Kersh Fowlers End (2001) 58: Watch out for Yudenow, sonny—he’s dead dangerous.
1959		C. Himes Crazy Kill 46: All right, son, let’s have the facts without the comedy.
1960		(con. WWII) G. Sire Deathmakers 280: You’re on your own now, sonny-boy.
1961		Galton & Simpson ‘Going Down’ Hancock’s Half-Hour [TV script] Look sonny, don’t show off in front of the young lady.
1965		C. Brown Manchild in the Promised Land (1969) 129: Yes, son, I guess I’m giving you the same chance you had before.
1972		R. Barrett Lovomaniacs (1973) 43: Don’t go all baby-faced on me, sonny-boy.
1977		A. Bleasdale Who’s Been Sleeping in my Bed 111: ‘Now listen here, Sonny Jim—’ ‘Who’re you callin’ Sonny Jim?’ Mad Dog said.
1980		M. Thelwell Harder They Come 176: Look on me, son.
1992		V. Headley Yardie 104: So, how’re you doing, son?
1993		R. Doyle Paddy Clarke Ha Ha Ha 228: Bedtime, sonny jim.
2000		Guardian Guide 1–6 Jan. 18: The mutt’s nuts, son.
2008		M. Herron Reconstruction: (2019) 158: ‘Sonny Jim wasn’t talking to me’.