When we find something funny, we usually type "LOL" or "Haha" as a shorthand to express that what was said made us laugh. In Korea, you will see people text the character kieuk or "ㅋ" in succession. The number of times it is used doesn't matter; the more, the better!
So, what is the explanation for them using "ㅋㅋ"? " The character "ㅋ" makes an aspirated "k" sound. Make that sound repeatedly, and it sounds like snickering. Sometimes they use the character "k" in succession as well, which means the same thing.
Examples:
a.) ㅋㅋㅋ...That's funny!
b.) You look ridiculous kkkkk
For a more in depth pronuciation guide, watch this video:
Another way to signify laughter via text is using the Korean character for h, which is "ㅎ" repeatedly to mean "haha" or "hehe" or "hihi". You can simply type "ㅎㅎ" by itself, and people will usually understand it instantly, but you can also add the vowels if you want to.
That will look like this:
a.) Haha - 하하
b.) Hehe- 헤헤
c.) Hihi- 히히
The next time you're texting with Korean friends, surprise them by slipping these into casual conversations!