Green’s Dictionary of Slang

a hooligan youth.

1967		‘Whisper All Aussie Dict.’ in Kings Cross Whisper (Sydney) xxxix 4/4: scally: Shortened scallywag, knockabout.
1983		R. Aven-Bray Ridgey-Didge Oz Jack Lang 45: Scally Scallawag.
1998		K. Sampson Awaydays 5: They look smart, miniature scals in cords, trainies and Adidas windcheaters.
1999		Guardian Sport 8 Jan. 16: The biggest bunch of piss-takers and scallies in football.
2000		Guardian Guide 8–14 Jan. 69: Jon Pritchett [...] accidentally shot a couple of young scallies attempting to break into his wine warehouse.
2007		Indep. 1 June 20: Other regional insults [...] include ‘scally’ on Merseyside.
2013		K. Sampson Killing Pool 153: The big players are now exactly the same brazen scallies as we’ve been after since the eighties — just richer.