Green’s Dictionary of Slang

(Aus.) to pretend to be what one is not, to act under false pretences; thus falsing n., shamming, malingering.

1948		Smith’s Wkly (Sydney) 25 Dec. 6/3: ‘I’m sick and tired of actors and suchlike who keep falsing to me so’s they can get more sugar out of me’.
1955		‘No. 35’ Argot in G. Simes DAUS (1993).
1962		C. Rohan Delinquents 104: ‘He’s in the States.’ ‘Yes, sure.’ ‘He is, Dawn, no falsing.’.
1967		‘Whisper All Aussie Dict.’ in Kings Cross Whisper (Sydney) xxxiv 4/5: falsing: Pretending, feigning illness.
1971		J. McNeil Chocolate Frog (1973) 40: Shirker: Remember? Tosser: (wryly) Whadder you think? Course I do [...] all of it. Shirker: (doubtfully) I reckon yer falsin’, china.