Australia is a country in the continent of Oceania, the Simpsons visit it when Bart makes a prank call asking what way the water goes. Bart then leaves the phone off the hook, raking up a huge bill for them as he made a reverse call. The guy sues him and Bart has to travel to a court in Australia. He ends up letting Bart Junior (a bullfrog) free and this makes a lot of bullfrogs in Australia, which there weren't previously.
Bart ended up calling an Australian bar using Dennis Leary's stolen cell phone to play a prank call. Specifically, he called a Australian Bar called Crocodile Dunkee requesting for a "Drew P. Wiener" causing the barkeep to call out for the person and stating "I have in my hand a "Drew P. Wiener", causing the patrons to laugh at him and tell him that he'd "better put it down, mate!", to the barkeep's frustration.
The Real Flag.
The Map
Flag (Simpsons)
The flag depicts a boot kicking a butt in the show, but this isn't accurate to the real-life flag, which features the Union Jack and the Southern Cross. In later appearances of Australia, the true flag is used.
Punishment
Long ago, in Australia, they used corporal punishment, the most popular of which was a boot kicking a butt. Bart was sentenced to this punishment. This is fictional as with the flag dipicted on the down under episode
Appearances
Episode – "Rosebud" 
Episode – "Bart vs. Australia" - Episode – "Principal Charming"
- Episode – "Lisa Gets an "A"" (Mentioned)
- Episode – "Pray Anything"
- Episode – "Lost Verizon"
- Episode – "The Color Yellow" (Mentioned)