It is not just a word, it is a way of life. It means, either you give 100% or you are worthless. Can also mean you received a perfect score/100% on an assignment. Either you get a hundo, or you're dunzo.

Dunzo Sonzo is a combination of two phrases Dunzo meaning "finished" and sonzo meaning "friend" that expresses the completion of plans or events.

Having a difficult task finally completed that you thought would never get done,said word is screamed at the top of the lungs to inform the world around you that the drama is fucking DUNZO!! pronounced (done-zo)