사족을 못 쓰다 – Korean Idioms #21
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If you like something so much, and you can admit that you are addicted to it in some level, then you will try to get it whatever it takes or do it even if it is really hard.
"사족을 못 쓰다" is the expression used for this situation. 사족 means four feet. Actually, it is used for animals, because they usually have four feet, but it is sometimes used to decribe 2 hands and 2 feet of a person. 사족 in 사족을 못 쓰다 is a rare case for this. 못 쓰다 means "cannot be used." So, 사족을 못 쓰다 means "You cannot use your hands and feet."
If you meet something you really like, your brain stops its analysis function and you just follow the guide of that thing. You can move your body but you cannot move it with your will. So, 사족을 못 쓰다 means "You really love something so much that you cannot move your body with your own will."
그는 소설책이라면 사족을 못 쓴다.
He really loves novels.
김치를 못 먹는 외국인도 있지만, Jessica는 한 번 먹어본 후로 그것이 사족을 못 쓸 정도로 좋아하는 음식이 되었다.
There are some foreigners who cannot eat kimchi, but Jessica ate it once and it became her favorite food.
그 형이 컴퓨터 게임이라면 사족을 못 쓰는 사람이었는데, 얼마 전에 보니 그 많은 걸 다 끊었더라.
I knew he was addicted to computer games, I found out not long age that he quit them all.
Final note to the expression
Some Koreans misunderstood "사족을 못 쓰다" as "사죽을 못 쓰다." But this is a wrong way of saying this, so don't mimic it.