~고말고 (go-mal-go) – of course/that’s right
~고말고 is quite similar to 그럼 in terms of meaning but quite different in terms of usage.
You can reply any question by saying 그럼 but you would need to attach ~고말고 to a verb.
In fact, in some cases, you would combine 그럼 and ~고말고 to emphasise on the confirmation or acknowledgement.
Examples: (너의) 어머님은 요리 잘 하니?
Does your Mom cook well?
그럼 요리 잘 하고말고. 그리고 엄마 만든 음식이 다 건강해.
Of course she cooks well. And all the food that she makes is healthy.
나 결혼할 때 내 결혼식에 오는거야?
When I get married, will you come to my wedding celebration?
그럼 가고말고. 나 가지 않으면 내가 무슨 친구야?
Of course I’ll go. If I don’t, what kind of friend am I?