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.
This word is used adverbially in the north of England, as in the united states, when anything vanishes, or is gone suddenly; as, whap went the cigar out of my mouth.
Origin: Cf. OE. Quappen to palpitate, E. Quob, quaver, wabble, awhape, wap.