Green’s Dictionary of Slang

(Aus.) male underpants.

1920		Nepean Times (Penrith, NSW) 7 Aug. 3/5: A fair amount of evidence was given concerning Michael’s whereabouts. [...] You can generally depend on it that a man is to be found in the same place as his ‘wear-abouts.’ But some lucky chaps have two pairs each, and if the police be not careful they may be tracking down the wrong pair.
1923		Toodyay Herald (WA) 17 Mar. 6/3: He said he had dived 132 feet and had then lost his wearabouts.
1936		Queenslander (Brisbane) 4 June 10/1: To make matters worse [...] the intimate scar or birthmark, hidden by his wearabouts is metaphorically exposed to the public gaze.
1941		Baker Popular Dict. Aus. Sl.
1953		Brisbane Teleg. 18 June 17/2: [advert] Jack Frost would fight a losing battle against these woolly wear-abouts which combine this season’s two fashion extremes - the slim silhouette for frocks and suits, and the full, swingback line of the tent coat.
1955		N. Pulliam I Travelled a Lonely Land (1957) 241/2: whereabouts – a man’s underpants.