Urban Dictionary: fully sick
I'm not sure if it's originally Australian, but you can do the research.
Student or Learner
In this thread, Raymott said that "fully sick" is used in the same sense as "wicked (very good)". Is "fully sick" AU English?
Are there any AE / BE speakers who use "fully sick"?
I have Australian and New Zealand friends that use this phrase. Also while working in London I heard young teenagers use it as well in the same sort of context.
That's sick man = That's cool, that's awesome.....
I have never heard an adult in the UK (London) use this phrase though, just the teenagers!