Green’s Dictionary of Slang

(Aus.) loafing, resting, having a nap; thus spinebasher n., an idler, a loafer; spinebash n. and v.

1941		Argus (Melbourne) 15 Nov. (Supplement) 1/4: I have knocked out a rough glossary of Australian army slang [...] Spine Bashing: Having a rest; loafing .
1943		Sydney Morn. Herald 11 Dec. 7/3: A soldier who spends an unnecessary time sleeping is a ‘spine basher’.
1944		J.D. Porter Our Fertile North 75: Most of the company ‘spine-bashed’ during the day. [...] ‘Spine-bashing’ had by now become an accepted item in the day’s doings, and the few hours rest after the midday meal proved most beneficial.
1948		S.L. Elliott Rusty Bugles I iii: gig.: The big spine-basher . . . [...] ot.: He’s just a great big lazy runt.
1951		Argus (Melbourne) 11 Dec. 5/1: They’ve Taken ‘Bash’ Out of ‘Spinebash’. [...] National Service trainees now have soft mattresses.
1953		I. Bevan Sunburnt Country 130: Spinebashing is sleeping.
1955		Argus (Melbourne) 15 Oct. 5s/7: [epitaph] I’ll spinebash here until last bugle-call / [...] / I’m A.W.L. — and I won’t be back.
1964		Aus. Women’s Wkly 1 Jan. 24s/3: They set great score by physical fitness [...] with lots of car-riding and spine-bashing in between.
1968		S. Gore Holy Smoke 52: He’s so crook in the guts that he’s down at the blunt end o’ the boat havin’ a spine-bash.
1972		G.W. Turner Eng. Lang. in Aus. and N.Z. 106: Lying down and doing nothing, what the Australian calls spinebashing.
1972		A. Chipper Aussie Swearers Guide 40: A pithy alternative [i.e. to layabout] , less frequently used, is spinebasher.
1987		M. Bail Holden’s Performance (1989) 280: He’s taken a bit of annual leave and I’ve been having this spinebash myself.
2003		McGill Reed Dict. of N.Z. Sl. 197: spine-bashing Sleeping or resting, originally on your bunk or stretcher to WWII Anzac soldiers, much more desirable than parade-ground bashing.