Green’s Dictionary of Slang

blow me down! excl.

also blow me backwards! ...down and call me Cocky! ...down with a fencepost!

a mild expletive.

[US]E.C. Segar ‘Popeye’ Thimble Theatre series No. 1 n.p.: Blow me down! a Injun!
[US] ‘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.
[UK]Gloucs. Echo 8 Mar. 3/5: [picture caption] Blow me down! I just can’t remember what the original colours were.
[NZ]D. Davin For the Rest of Our Lives 108: Well, blow me down, God’s got a flying start.
A. Baron With Hope, Farewell 141: ‘Well, well, well. Blow me down and call me Cocky!’ Aubrey met them boisterously.
[Aus]D. Niland Shiralee 140: Blow me down, wonders’ll never cease.
[NZ]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.
[Scot]Dandy Comic Library No. 205 41: Well, blow me down!
[Ire]J. O’Connor Secret World of the Irish Male (1995) 204: ‘Aw, blow me backwards,’ he groans.
[NZ]McGill Reed Dict. of N.Z. Sl. 25: blow me down with a fencepost! I am surprised.
[UK]K. Sampson Killing Pool 141: Blow me down if it isn’t Alfie Manners, gurning at me through the glass partition.