[Korean grammar] -기가 무섭게 Expressing the Ordering of Behavior

가: 어제 정말 재미있었죠? 놀이공원에 가서 그렇게 즐겁게 시간을 보낸 게 몇 년 만인지 몰라요.
Wasn’t yesterday a lot of fun? I don’t know how many years it’s been since I’ve had so much fun at an amusement park.
나: 네, 오랜만에 신나게 놀았더니 재미는 있었는데 많이 피곤하더라고요.
Yes, it was great to have some fun for the first time in a while, but it was really tiring.
가: 저도요. 어찌나 피곤한지 저녁 먹고 수저를 놓기가 무섭게 쓰러져서 잤어요.
Me too. I was so tired that I went right to sleep as soon as I set down my utensils after eating dinner.
나: 저는 신발 벗기가 무섭게 방에 들어가서 옷도 안 갈아입고 잤어요.
I went straight to my room as soon as I took off my shoes and fell asleep without even changing clothes.

This expression is used to emphasize the fact that something occurs immediately after something else ends. The word 무섭게 is the conjugated form of the adjective 무섭게 and this expression means that the succeeding action happens in a frighteningly short time after the completion of the previews action. The form -기 무섭게 is also used. This expression only attaches to verbs.

• 결혼하자는 말을 꺼내기가 무섭게 거절해 버렸다.
As soon as he said we should get married, I refused.
• 저 식당은 음식이 맛있어서 문을 열기가 무섭게 손님들이 모여든다.
That restaurant is so delicious that as soon as it opens, it fills with patrons.
• 그 작가의 책은 마니아 층이 형성되어 있어서 출판되기 무섭게 다 팔려 버린다.
That author’s works have reached the status of a craze as they fly off the shelves as soon as they are released.

While this expression can be replaced with -자마자 with no major change in meaning, it carries the nuance of exaggerating an even faster transition between actions compared to -자마자.
• 결혼하자는 말을 꺼내자마자 거절해 버렸다.
• 그 작가의 책은 마니아 층이 형성되어 있어서 출판되자마자 다 팔려 버린다.