ククク

ククク, クックックッ, くっくっくっ, くくっkukuku

interjection · adverb

1. mwahahaha (evil laughter)
2. coo coo
3. cooing
4. sound of pigeons
5. sound of doves
6. stifled laughter
7. suppressed laughter
8. sound of snagging

Study it in Yanamino