A tourist from Hong Kong walks into a Sydney Exchange Bureau with HK$900 and asks for A$. The teller checks the day's rate, and hands over A$120. The grateful tourist says, "Thank Velly mutch! Velly kind!" and walks off to Kings Cross.
The next day, the Hong Kong guy goes back, with another HK$900 and hands it over. The teller checks the rate, and hands over A$135. The Hong Kong guy is very happy, and quickly pockets the cash and disappears, chortling to himself, "This Aussie velly bad math. Ha, ha, ha, ha."
The following day he returns, again clutching HK$900 in crumpled notes. He hands it over to the nonchalant teller, who checks the rate, and hands over A$96.
The Hong Kong guy does a double take, recounts the notes, and fixes the teller with an incredulous stare. "Hey, Terrer, yesterday I come wif money, you give many many dorrar, ormos' One-hun'red-firty-five! Day before, you gif one-hun'red-twenny, Today you give onry nin'ey-six. Why you do to me like this?"
The teller replies calmly, "Fluctuations Sir."
The apoplectic tourist screams back, "Fluck You Aussies Too!"