It's when you Diss someone so hard that he doesn't know what to answer. He might be really ashamed or humiliated.
It's mostly used in the ghettos of Montreal.
(Talking to your neighbor named Jo)
-I think you should install curtains Jo.
-Why is that?
-I've seen you fucking with your dog yesterday night.
(Now Jo is Diss Bono)
Diss Bono is an expression used mostly in Montreal's ghettos. It's the kind of thing you may say just after insulting someone very hard. It's used only when the person is totally destroyed and can't reply anything.
-How are you Jo?
-Well and you?
-You're a little bastard! DISS BONO!