sound of a kick against someone’s body (head, for example) (“Shonen Jump, Dragon Ball”, manga comic by Akira Toriyama), also: bwak, bwok, glok, klam, klok, shwap, thwogg, whack, wham, wap, whap, whop, whump
onomatopoeia: 1. the naming of a thing or action by a vocal imitation of the sound associated with it (as buzz, hiss) 2. the use of words whose sound suggests the sense