I have here a list of sound effects that I've either
encountered in manga's or made up myself. They are divided
into the action the character is doing. It'll also give
you some ideas and get you started on your own sound effects.
For example, some of the sound effects are pretty much the
same except for one slight spelling change like whap
and wap or tok and thok.
For more sound effects, refer to your favorite manga or comic book. Listen closely to sound effects in shows, real-life, the radio, and even a book. Experiment a bit and develop your own sounds!
ha ha haaa
Uwah ha ha
Ya haa haa