Green’s Dictionary of Slang

(Aus.) a form of catapult (sometimes without the forked stick that characterizes the shanghai n.² (1)

1903		Bulletin (Sydney) 17 Dec. 35/1: He had in his pocket a ‘ging’ with a shop-made wire prong, a ‘ging’ of marvellous power and deadly accuracy.
1915		N. Lindsay Norman Lindsay’s Bk II 79: He had even knocked a parrot with his ‘ging’, but the parrot is an indomitable bird [AND].
1933		N. Lindsay Saturdee 152: Peter took out his ging to make a show of catapulting a stone at a non-existent bird.
1941		Baker Popular Dict. Aus. Sl.
1950		Arna (Sydney) 5: He put the ging back in his hippocket, and practised whipping it out and loading and shooting as fast as he could [AND].
1968		S. Gore Holy Smoke 14: But when he comes rushing up – spittin’ chips, he’s so mad – young Dave only lets fly with one shot outa his ging, and the big bloke’s stonkered.
1980		W.H. O’Rourke My Way 286: In my boyhood days, every boy had a ‘Shanghai’, or ‘ging’, as it was more generally known, and no bird was safe [AND].
1986		R. Beckett Dinkum Aussie Dict. 26: Ging: In the States of Western and South Australia a child’s word for a shanghai.
1993		Aus. Word Map 🌐 ging [...] ‘When growing up in East Gippsland, a shanghai was a forked stick or wire with rubber-bands attached, while a ging was a length of bicycle inner tube used for the same purpose, but without the forked stick. One end was gripped in one hand, wrapped back over the thumb. The other end had a leather pouch attached for the projectile’.