I think he meant "sick" as in "Fully sick mate!"

.. that means good....

Like the teenage boys who put overboosted turbos in small 4 cylinder cars and drag race each other from traffic lights and then sit around having frappucinos in the local cafe comparing notes and bragging about how "Fully Sick my car is now wiv duh new Mag wheels bro...."

...not that there is anything wrong with that...