Over doors, around and through banisters, fences and railings. One year, I hosted an Olympic party and passed out IDs, laminated on chains, calling each person something different. Party411's Custom Creations department can make IDs for you. Australian, of course. If you have the budget, have The Outback Restaurant cater your Olympics.
Australian fare includes Aussie BBQ meats.
If you are celebrating someone's birthday, you may want to do things like passing the birthday torch, a birthday cake-eating race, a birthday hat heat, a birthday bash dash, etc. Divide the group into 2 teams and line them up. Have the person in each line grab a handful of sand from a container. They must pass the sand to the next player, who passes it to the next, and so on down the line. The team with the most sand wins the game.