ㄱㅅ this is short for 감사 (gamsa) meaning “ty” or “thank you”
ㅁㄹ this is short for 몰라 (molla) meaning “idk” or “I don’t know”
ㄴㄴ this is short for 노노 (nono) meaning “no no”
ㅋㅋ this is short for 크크 (keukeu) meaning “lol” or simulation of laughing out loud
**Hope this helps**
