adverb, adverb taking the 'to' particle, noun or participle which takes 'suru'
Describes acting without shame or embarrassment, often in a situation where one should feel guilty or awkward. Can also imply a calm, unflustered demeanor.
彼は遅刻しても、しゃあしゃあとしている。
Even when he's late, he acts completely shameless.
Even after lying, he was smiling brazenly.
adverb, adverb taking the 'to' particle
fast flowing (of water)
Describes water flowing swiftly and smoothly, often with a sense of ease or lack of obstruction. Less common than the shamelessness sense.
川の水がしゃあしゃあと流れている。
The river water is flowing swiftly.