These are words I have used in my emails to my overseas friends that they didn't understand, or things we have here that you don't have, or are different overseas. New words will be added as we use them...

Fair Dinkum	This is probably the most Aussie term ever. It means REAL or REALLY. If you say "I climbed over the Harbour Bridge yesterday" then your friend would say "Fair Dinkum?" (meaning did you really?). If someone doesn't believe what you have told them you would say "Yes, mate, I'm Fair Dinkum!"
Ice Block	This is not just a block of ice. You might call it a popsicle. It can be a water ice block with fruit juice or a flavour like Lemonade or Cola. Or it can be a milk ice block which is like a frozen milkshake on a stick.
Jelly Babies	Not to be confused with Jelly Beans. These are soft jube lollies shaped like little people. My favourite are the red ones.
Lemonade	Our Lemonade is not the same as American Lemonade because ours does not taste like lemon! We think it is the same as Sprite or maybe 7-UP.
Lollies	In America these are usually called sweets or candy. They can be anything from chocolates to licorice, jelly beans to barley sugar. My favourites are snakes.
Pie with Sauce	In Australia one of the most eaten types of fast food is the Meat Pie. Just like an American Apple Pie but full of beef, or mince. Sometimes with potato on top called a Shepherd's Pie, and sometimes with mushy green peas on top called a Pie Floater. Sauce is Tomato Sauce which is called Ketchup in America. A slang name for a pie is a Mystery Bag because sometimes we don't know exactly what is inside it. In old fashioned Rhyming Slang it is called a DOG'S EYE with DEAD HORSE. Pretty gross!
Bonza	Old Aussie slang for something really good. Someone might say "Wow Dana, this sure is a Bonza website!"