Such as when you pop a gyoza in your mouth and the juices from the broth and saliva start to flow.
Possible SFX: POING, TWANG.
This actually means manga readers have an edge over traditional book-readers.
SFX: squelch, schwik, schlik.
Often used in doujinshis to indicate that a character is moved beyond words, stunned beyond words, or just generally beyond words.
Also used when lightly brushing or sliding against something.
Lately Japanese manga artists began to use this SFX to expresses the unknown voices or sounds.
I wanted to provide examples of Hiragana sound effects in addition to Katakana.