How do you ask "Are you kidding me?" in Korean? Or is there a phrase similar to it?

First notebook entry: Introducing myself 안녕하새요 I am trying to learn 한글. This is a self-learning process. I like learning about different cultures especially asian. I was born in India but now I have been in the USA for a few years now. I can speak Hindi, Marathi, English fluently. I can also speak Sanskrit. I know the basics of German but I have sort of forgotten a lot of stuff lol. Anyways so I am very much into Korean dramas, music, movies, culture. I would love to learn this language and be able to communicate efficiently. 감사함니다, 디비가 (Dipika).