Wiktionary
thwock
alt. To hit someone, playfully, but hard. vb. To hit someone, playfully, but hard.
Usage examples of "thwock".
He alit with a clanky jingle of armour and the thwock of leather-shod, wooden swordsheath against his leg.
As I went through the gate I could hear the thwock of tennis balls on catgut, and the occasional burst of applause.
The helicopter bounced and shook in the soup as they thwock thwock thwocked toward the shore.
He heard the thwocking of at least one more helicopter and knew that more could not be far behind.
But no thwocks came, and soon he was running lightly and easily down the road.