[Bloody Sam Roberts]

I fail to understand the use of the word “sick” in today’s parlance.....

It may be a New England thing....like "wicked"...meaning 'extreme'. I don't get out of MA much but the 'sick' thing is used a lot up here.

[Vendome]

Nah, we use here in California too.

That was Sick! i.e. wicked, cool, gnarly, bitchin’, Dude!, etc,