Green’s Dictionary of Slang

a general term of address to a male.

1877		W. Hanna (ed.) Letters of T. Erskine 302: To another younger grandchild she said, ‘My darling, God does wish you to be so good; God does not only say, “Boysie, you must not do this,” “Boysie, you dare not do that,” but “My child, take My hand and walk with Me”’.
1906		J.W. Carr ‘Words from Northwest Arkansas’ in DN III:ii 128: boysie, n. Dear boy. (N.E. Ark).
1912		Bath Chron. 16 Nov. 6/7: ‘My Boysie’ [...] when he smiles the sweetest smile of all.
1925		West Australian (Peth, WA) 11 Dec. 11/5: Let shrinking ‘Boysie’ address himself in like manner.
1929		I. Cameron [bk title] Boysie.
1934		C. Stead Seven Poor Men of Sydney 328: Tired, boysie?
1941		Courier Mail (Brisbane) 8 Aug. 3/2: Come on now, boysie, you go first base, and I’ll throw.