If you're referring to the 'Watata' superchat sound-effect that was created by the VTuber 'Kaela Kovalskia' (hololive), then it's one of her own ways of expressing excitement.
Context: Youtube Stream of 'Kaela Kovalskia'
*Someone donates to her (superchat)*
*Superchat donation message shows up on screen, playing the 'Watata' sound-effect*
*Someone donates to her (superchat)*
*Superchat donation message shows up on screen, playing the 'Watata' sound-effect*
by Anonyhamster December 29, 2023