1. $1 or $2 coin
2. gold coin donation
Lots of charity events and amateur sporting events have "gold coin donation" on their flyers and adverts and there's someone at the gate with a bucket for you to chuck your gold coin into. Not chucking in a gold coin is considered stingy (pronounced stin-jee) and the person not chucking it in is a bloody mongrel.
family jewels, groin
Usage example: Yelled at strippers by straight blokes in pubs, "Gorn! Show us yer map of Tassie!"
gossip, skinny, info, news
So "Gimme the goss" means "What's the skinny?".
Davo: "Hey, Simmo, how are ya?"
Simmo: "Orright. Whatcha up to?"
Davo: "Gotta pop in the bottle shop for some grog for the barbie."
undies, underwear, knickers, jocks, pants
Australian rhyming slang. Reg Grundy (TV producer or summat) + undies = grundies.