Green’s Dictionary of Slang

throbber n.

(Aus.) a testicle.

[Aus]J. Byrell Lairs, Urgers & Coat-Tuggers 200: ‘If it’s a dud then I’m down a couple of hundies, that’s all. But, on the other hand, if it ain’t a dud ... ‘n’ I am willing to bet my left throbber that it ain’t .