Green’s Dictionary of Slang

1. toys, baubles.

1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue n.p.: Gingambobs, toys, bawbles; also a man’s privities.
1811		Lex. Balatronicum.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.

2. the testicles.

1672		J. Phillips Maronides (1678) VI 73: Evadne all in Mulligrubs / For her spruce Ushers gingombobbs.
1785, 1796, 1811, 1823		see sense 1.