I am wondering on the use and the meaning of the word fertig in this sentence:
Bist du fertig?
In Italian a similar expression could be “Ma sei fuori/matto?” in the sense of “You are crazy!” In my personal opinion this expression can also be used as a joke in order to tease someone. I don’t take it as a personal offense.
I would really like to know what the usage and meaning of “Bist du fertig?”, is. Is it offensive in German?