A slang term from San Francisco, used by teenagers meaning: To get EXTREMELY drunk. You are not getting truly "Hella Irish" unless you are drinking a 40 in a North-face jacket. When people say "Hella Irish" they often do the Shaka hand sign, except they make it seem as if they are drinking from a bottle. These teenage boys often get "Hella Irish" at a magical place called "The Grove"
Jack: What happening this weekend?
Danny: We were all going to the grove, Hella Irish!
Jack: I'm so it! Lets get HELLA IRISH!!!