Whap

v. i.	1.	To throw one's self quickly, or by an abrupt motion; to turn suddenly; as, she whapped down on the floor; the fish whapped over.
v. t.	1.	To beat or strike. [imp. & p. p. Whapped ; p. pr. & vb. n. Whapping.]
n.	1.	A blow, or quick, smart stroke.

Thesaurus

Verb

1.

whap - hit hard bash, sock, whop, bonk, bop hit - deal a blow to, either with the hand or with an instrument; "He hit her hard in the face"