"Of course" is "당근이지"(tang-gŭ-ni-ji) in Korean.
Dang geun e ji (of course) is youth words. Originally, because "Dang yeon ha ji (당연하지)" is complaining representation but is correct that, Dang-geun (당근, carrot) is referred to in this way from the fact that similar in sound to. Representation to be used only in each other friends.