thwacks

noun
  1. 1

    The act of thwacking; a strike or blow, especially with a flat implement.

  2. 2

    A heavy slapping sound.

verb
  1. 1

    To hit with a flat implement.

  2. 2

    To beat.

  3. 3

    To fill to overflow.

Source: https://en.wiktionary.org/wiki/thwack, https://en.wiktionary.org/wiki/thwacks