This is an expression. It can be used to express joy, amazement, not interested and so on. It was formed in Nigeria.
by Jack2.0 January 2, 2020
Biola: I just got a new set of earpods

Deola: For real? Mad o!
by Phemmy POKO January 5, 2020
A very Mumbai way of saying 'are you crazy or something?' Generally used when someone suggests something stupid or ridiculous.
Shyam : Hey Shankar, you owe me 500 Rupees. How do you plan to pay it?

Shankar : I bought this lottery ticket and I am going to win. So I will pay you as soon as I win.

Shyam : You think I am mad-o-wat to believe that?
by mad-o-wat January 24, 2010