Green’s Dictionary of Slang

back-to-front; thus fig. messy, chaotic.

a.1865		A. Lincoln in Coll. Works VIII 420: He said he was riding bass-ackwards on a jass-ack, through a patton-cotch, on a pair of baddle-sags, [etc.].
1930		(con. c.1900) Shoemaker 1300 Words n.p.: Bass-ackwards – head over heels, a tumble.
1947		E. Taylor Richer by Asia (1966) 99: We are always saying to each other: Look how backassward these Indians are.
1948		P. Green Common Glory 238: But so it is that other good men be persecuted in the godless days of this bassackward world.
1949		PADS 11 3: Bassackwards [...] totally backwards. A euphemistic Spoonerism.
c.1960		in Hench Coll.
1965		H. Rhodes Chosen Few (1966) 91: Another case of man’s almighty faculty for making bass ackwards decisions.
1979		Maledicta III:2 248: Some US (Pig Latin agfay) and UK (Cockney and camp words such as riah – hair) in words do appear spelled bassackwards.
1982		W. Wharton Midnight Clear 56: I’m getting better at playing this inside-out, bass-ackwards kind of bridge.
1991		M. Amis Time’s Arrow 48: Tod’s cruelty would be trashy, shitty, errant, bassackward.
2005		M. Denman Daily, Before Your Eyes 114: Not as absurd as the whole idea of capital punishment, but it ranks right up there as backassward stupidity.
2006		M. Braun Tenbow 162: ‘You’ve got things bassackward,’ Stillman informed him. ‘You’re the one that has to come up with proof.’.
2017		Twitter 23 Aug. 🌐 America has the back-asswards Calvinist streak where calling for the expulsion of non-white races is just a difference of opinion.