I noticed the following comments under a hot meta post: [Downvoting questions from new users][1]

> - I agree this is horribly bad form. I blame the Australians. – *Andrew*
> 
> - But *@Andrew*, as you yourself pointed out, there are no Australians here. – *StoneyB*
> 
> - *@StoneyB* No, actually I said I never see them. They could be all around us, waiting in the trees like downvoting drop-bears,
> whispering, "Strewth, she's a beaut isn't she!" when they see their
> next victim. – *Andrew*

At first, I thought these comments to be rude and offensive, yet the upvotes suggest that they are not. I guess it's a well-known joke, but searching "blame the Australians" online didn't give me any useful information.

My question is: Why are Australians blamed?

  [1]: http://meta.ell.stackexchange.com/q/3396/31745