What is Hardk0re?
1.
the word harcore to the millionth power.
Bob: Dude, he's so hardk0re!
Joe: Yeah I know, I wish I was like him!
See
2.
When something is extreme. It is sometimes shorten to just 'hard'.
Conan - Craig has drunk 34 beers and all of Pats bourbon.
John - He's Hardk0re!
Pattus - NO, he's a dickhead.