Green’s Dictionary of Slang

lowdown adv.

[lowdown adj. (1)]

meanly, contemptibly, unpleasantly.

[Aus]Truth (Sydney) 11 Nov. 5/7: This was ‘playing it low down’ on the country with an Imperial vengeance.
[UK]‘Doss Chiderdoss’ ‘The Hand-Shaking Peril’ Sporting Times 18 July 1/3: You’ve been playing it low down on me, / But we’ve shaken hands now, and are quits!
[Aus]Kia Ora Coo-ee 15 Aug. 17/1: After I’d been in Hospital for about three weeks, they treated me pretty low down, I thought – took me off ‘light diet’ and sent me into the ‘bull ring’ for meals.