Turn of Phrase

Yesterday at our Uke Jam, it got to my turn to choose a song and I looked at my friend for a suggestion and so we went with Edelweiss.

Everyone smiled, "Oh, another waltz?  Why do we keep choosing waltzes tonight?"

My friend and I looked at each other and started laughing.  "We should do Waltzing Matilda!"

When it got around to the lady who had heard our conversation, she chose just that song.

Did you know?  Waltzing Matilda is not even a waltz.  And it has nothing to do with dancing either.

But no matter, we were in a mood to laugh and we played it.  As I strummed through the chords (or tried to) and sang along, I would throw horrified glances towards my friend.  "They're going to arrest this guy?"

I suddenly realized, I had no idea what this song was really about.

So, I looked up the lyrics.

Once a jolly swagman camped by a billabong
Under the shade of a coolibah tree,
And he sang as he watched and waited till his billy boiled:
"Who'll come a-waltzing Matilda, with me?"

Waltzing Matilda, waltzing Matilda
You'll come a-waltzing Matilda, with me
And he sang as he watched and waited till his billy boiled:
"You'll come a-waltzing Matilda, with me."

definitions:

swagman: an itinerant Australian laborer who carries his personal belongings in a bundle as he travels around in search of work.

billabong: A branch of a river forming a backwater or stagnant pool.

coolibah tree: a type of Australian eucalyptus tree

billy: a camping pot used for boiling water

waltzing: to travel while working as a craftsman

Matilda: a term for the swagman's bundle

Essentially, it's a song about a man who travels around looking for work who is cooking himself some food by a river. In the rest of this song, the man kills a sheep to eat it and is approached by policeman who want to arrest him for stealing property from a squatter (side note: who is technically stealing property from someone else). The man refuses to be taken in and kills himself instead and his ghosts haunts the area.

English baffles me.  English baffles me.  English baffles me.  

I only knew the definitions of half of the words in that song.  How did I figure out what I did in that song?  

How do people ever learn this language as a second language?  

And why, oh why, oh why, do Australian people sing this at sporting events?