어쩌다가 + Verb
Let’s take a look at the pattern 어쩌다가 + Verb. You would understand this note much better if you have read our note on –다가. This is an interrogative sentence that focuses on the action that led to another action. For example, your son got home crying over his wound. He said he tripped off and fell. Of course, it would not happen if he walked properly so you want to ask how it happened- what he did that cause him to fall or what he exactly did before he fell. Imagine that action as a continiouus and not an abrupt and short one. The verb at the end must be in past simple form.
How did you fall?
How did you get hurt?
어쩌다가 우리 같은 집에 자?
How did we end up sleeping on the same bed?
어쩌다가 그 사람 만났어?
How did you end up meeting that guy?
어쩌다가 간장 쏟았어?
How come you spilled the sauce?