Lines 

Dong-man：야, 계란죽.

Hey, egg porridge.

Ae-ra：뭐?

What?

Dong-man：너 이 시간에 아빠 만나러 갔다 온 거면 엄마 생겨서 갔다 온 거겠네?

If you went to see your dad at this time, you must have gone because you have a mom now? 

Ae-ra：너 어떻게 알았어?

Hey, how did you know? 

Dong-man：난 너에 대해 모르는 게 없어. 23년 내내.

I know everything about you. It’s been that way for 23 years.

Expression of the Week

어떻게 알았어? How did you know?

어떻게 – how, what

알다 – v. to know, learn, have knowledge, be familiar

Casual – 어떻게 알았어?

Semi-polite – 어떻게 알았어요?

Polite – 어떻게 아셨어요?

>>[어떻게 알았어?] is a question asking the listener how they knew, or found out about something with the verb “알다” which means to know. The speaker can raise the tone at the end of “알았어” to make it into a question.

>> In the dialogue, Ae-ra is surprised that Dong-man knew the reason behind her meeting with her dad, which is why she is asking Dong-man how he knew by using the expression “어떻게 알았어?“