Green’s Dictionary of Slang

blow me down! excl.

a mild expletive.

1931		E.C. Segar ‘Popeye’ Thimble Theatre series No. 1 n.p.: Blow me down! a Injun!
c.1940		‘Olive Oyl Assisted by Popeye & Wimpy’ [comic strip] in B. Adelman Tijuana Bibles (1997) 23: Blow me down it’s coming out of her mouth.
1944		Gloucs. Echo 8 Mar. 3/5: [picture caption] Blow me down! I just can’t remember what the original colours were.
1955		D. Niland Shiralee 140: Blow me down, wonders’ll never cease.
1963		B. Crump ‘One of Us’ in Best of Barry Crump (1974) 142: And blow me down if we don’t fly to Auckland that very afternoon.
1991		Dandy Comic Library No. 205 41: Well, blow me down!
1994		J. O’Connor Secret World of the Irish Male (1995) 204: ‘Aw, blow me backwards,’ he groans.
2003		McGill Reed Dict. of N.Z. Sl. 25: blow me down with a fencepost! I am surprised.
2013		K. Sampson Killing Pool 141: Blow me down if it isn’t Alfie Manners, gurning at me through the glass partition.