A commonly used kiwi slang term which is a polite way of saying "Fucked". Used in reference to something that is broken or sexual intercourse.
It can be used as a drop in replacement to the word "fuck" with the exception of the term "fuck you". No one says "root you". That's just weird.
"Ah shit mate. It's looks pretty rooted" - statement regarding a friends broken leg
"Yeah, it's fully rooted" - confirmation that your car is broken
"Hey you! Wanna root?" - drunken direct proposal for intercourse
"Yeah fully eh. They got pretty rooted at the last game." - observation about the opposing sporting team's loss of a game
"Hey bro, how you feeling?" "Fuck, I'm pretty rooted eh" - enquiry about last night with a confirmation that a hangover is present