Similarly, the sounds of giggling are 크크, 키키, 킥킥 etc.

But 클클 has final consonant ㄹ , 클 is composed of 크 + ㄹ. The final consonant ㄹ in giggling sound, it sounds more stronger than 크 with a bit of phlegm.

This is why the author Sun-woo Kim used 클클 for old people’s giggling sound in his poet, rather than just 크. Since old people’s vocal cords become raspy than young people, 클클 is fit better to old people’s giggling than just 크크. And also, 클클 is fit to witch’s giggling.

This is why Korean is great. Korean expresses very detailed and delicate.

not 클클 

it's 크크 

like haha or kkkk

Like kkkk