Japanese people use onomotopoea for almost everything. Here’re some of them:
Pigs – boo boo, Ducks – gaa gaa, Chicks – piyo piyo, Lion – gAooo, Babies -ongya ongya, Frogs – kero kero/gero gero/geko geko, Dogs – one one, Cats – nyaa nyaa.

Those are understandable but how about these:
Anger- poon poon, Sad – shiku shiku, Blushing – po, Hungry – peko peko, Spinning – guru guru, Embarrashed girls – ehe.

More?
Bowing hard – peko peko, Rubbing – suri suri, Drinking joyfully – gubi gubi, Applause – pachi pachi.

PG-13 area:
Peeing (men) – jobo jobo, Kissing – chu, Flirty noise – ufun (women use only), Drunken people – oui.

R rated:
Please refer to Mako’s comment.