Duh~

Duh~ 맞다구~ 당연하지~!

It means "Ye~~~s! Of course~~Why do you ask me?" We use this expression, when somebody asked a stupid question. Use this expression with friends not to boss! 

e.g) Is shane a man? Duh~. Shane is a guy's name of course he's guy. Duh~!

A: So, you have an online business?

B: Yes. I teach online.

A: Oh. So, you use a computer?

B: Duh~~!

A: 그니까 온라인사업을 하고있는거지?

B: 응. 온라인에서 가르쳐

A: 아. 그럼 컴퓨터 이용하는거야?

B: 당연하지~~