Green’s Dictionary of Slang

an oath orig. popular among upper-class dandies.

1780		M.P. Andrews Fire and Water! (1790) 25: Stab me! I don’t believe the French admiral’s taste is only for contemplation.
1904		Graphic (London) 9 July 11/1: ‘Come in, gentlemen; stap me, come in’.
1912		Bulletin (Sydney) 26 Sept. 15/4: A line of 27 telegraph poles ran through the paddock. Stap me if he didn’t ringbark every one of them.
1939		Dly Mirror 6 Dec. 23/3: [cartoon caption] Sta[ me! Now I can pluck myelf an armful of chaste charmer.
1945		Good Morning (London) 11 Sept. 3/3: [cartoon caption] Safe!! — Stap me — that was a close call.
1952		C. Harris Death of a Barrow Boy 58: Well, stap me!
1965		J.P. Carstairs Concrete Kimono 191: ‘Stap me!’ the intrigued Uncle Steve said increduously.
2000		Indep. Rev. 20 Mar. 3: Stap me!