Green’s Dictionary of Slang

John Brown v.

also john brown
[the abolitionist John Brown (1800–59), who was hanged for his part in the attack on Harper’s Ferry, Virginia]

(US) to execute by hanging; thus be John-Browned, to be ‘hanged’.

in M.M. Mathews Beginnings Amer. Eng. 160: You need apprehend nothing dreadful, for boobies seldom ‘John Brown’ each other [DA].

In exclamations

I’ll be John-Browned! (also I’ll be John Brown! I’ll be john browned! I’ll be Johnnied! I’ll be Johnny Browned!)

(US) a joc. euph. for I’ll be hanged! under hang v.1 .

[US]J.W. Carr ‘Words from Northwest Arkansas’ in DN III:i 84: John(ny) Browned, pp. In the exclamation, ‘I’ll be John(ny) Browned’.
[US]J.W. Carr ‘Words from Northwest Arkansas’ in DN III:ii 143: Johnnied, pp. In the exclamation, ‘I’ll be Johnnied’.
B.M. Bower Lookout Man 102: ‘I’ll be John Browned if she ain’t on to it already!’ Jack chortled.
[US]Atlantic Monthly Feb. 182/1: I’ll be john-browned if there’s a monkey-chaser in Harlem can gyp him.
[US]R. Fisher Walls Of Jericho 230: Well, I’ll be john-browned.
[US]S. Philips Big Spring 1: I’ll be John Browned if we didn’t have a dry norther that would send you hunting for your long ones.
[US]F.C. Brown North Carolina Folklore 1 555: John Brown, I’ll be... A mild imprecation .
[US] in DARE n.p.: I’ll be John-Browned.
Newell If Nothin’ Don’t Happen n.p.: Well, I’ll be John Browned, Uncle said [DARE].