Green’s Dictionary of Slang

1. (Aus.) a youthful gangster.

1900		Bulletin (Sydney) 10 Feb. 11/3: The ‘peb.’ paid his shilling, behaved decently, and catered for his own sad amusement, but evidently the gamble was the initial draw, and without it he would as soon trot his accordian and his girl ‘darn the bye.’.
1904		Sun. Times (Perth) 28 Aug. 4/7: A shy-eyed damsel nudged her escort, the latter a flash larrikan sporting a shrieking tie and a well-plastered down fringe. [...] ‘Well, look here,’ proceeded the she-peb, ‘when this ’ere rot’s over arst ’ees gills to play a cake walk’.
1916		C.J. Dennis ‘To the Boys Who Took the Count’ in Moods of Ginger Mick 102: They wus pebs, they wus narks, they wus reel naughty boys.
1959		Baker Drum 133: Peb, a larrikin.

2. see pebble n. (4)