Lobster, pineapple, gray nurse Australians don't barter with lobsters and pineapples, but most have had at least one friend ring them up (or hit them up at the pub) to lend a lobster or a pineapple. The $20 note being a sparkling red (lobster) and the $50 note being bright yellow (pineapple) lends itself to the phrase. The $100 note, a blue gray, has now been named after a shark (grey nurse). The less important $5 and $10 notes are often referred to as past international sporting stars -- Pam Shriver (fiver) and Ayrton Senna (tenner).