If you are interested in Korean culture, I think you need to know this song because 갑돌이 and 갑순이 are names that are used in a lot of jokes, including dirty jokes. Besides, 돌이 and 순이 are suffixes that refer to a man and woman, respectively, and are used in a lot of slang expressions. For example, 공순이 is a slang expression used to refer to "female factory workers," with 공 being an abbreviation of 공장 (factory).
Below are two videos. The first is of Serena Kim singing the song, and the second is of Yu Ji-na (유지나) singing it. I posted the second video because it also shows the lyrics.
갑돌이와 갑순이는 한 마을에 살았더래요
둘이는 서로 서로 사랑을 했더래요
그러나 둘이는 마음뿐이래요
겉으로는 음~ 모르는 척 했더래요
오~ 모르는 척 했더래요.
그러다가 갑순이는 시집을 갔더래요
시집간 날 첫날밤에 한없이 울었더래요
갑순이 마음은 갑돌이뿐이래요
겉으로는 음~ 안 그런 척 했더래요
오~ 안그런 척 했더래요.
갑돌이도 화가 나서 장가를 갔더래요
장가간 날 첫날밤에 달 보고 울었더래요
갑돌이 마음도 갑순이 뿐이래요
겉으로는 음~ 고까짓 것 했더래요
오~ 고까짓 것 했더래요.
"Kap Doli and Kap Suni"
It is said that Kap Doli and Kap Suni lived in the same village.
It is said that they both loved each other.
But it is said that they kept it only in their hearts.
It is said that outwardly, mmmmmm, they pretended ignorance.
It is said that Kap Suni eventually got married.
It is said that on her wedding night she cried endlessly.
It is said that in Kap Suni's heart, Kap Doli was the only one .
It is said that outwardly, mmmmmm, she pretended he wasn't.
It is said that Kap Doli got angry and also got married.
It is said that on his wedding night he looked at the moon and cried.
It is said that in Kap Doli's heart, Kap Suni was also the only one.
It is said that outwardly, mmmmmm, he (still) did the (sex) thing.
- 더래(요) is an verb ending that is used to report something that another person has seen or heard in the past.
- 고까짓 것 essentially means "그 것," which is an indirect way of saying he had sex. When you add 까짓 to such pronouns as 이, 고, 그, 요, 저, and 조, it trivializes them and can make them sound cutesy.
- I think the last line of the song is supposed to be funny.
POSTSCRIPT: There is an interesting and funny post HERE from someone who does not like the ending to the song and offers several suggestions for improving it. Also, he remembers hearing a fourth verse to the song, but he cannot remember what it was. Maybe, he was talking about the following version of the song, which has added another verse to the original.