Stolen from The Telegraph:
1) What do you call an Australian with 100 by his name? A bowler.
2) Why can't Aussies open bottles? Because they don't have any openers.
3) What do you call an Australian with a bottle of champagne in his hand? A waiter.
4) What do you call a world class Australian? Retired.
5) What do you get if you cross the Australian cricket team with an Oxo cube? Laughing stock.