whop (v.)

"a hit, a blow," late 14c., probably of imitative origin. The verb (late 14c.) originally meant "to throw quickly or with violence," and in slang c. 1560-1730 it meant "to copulate." Related: Wapped; wapping.

1767, "uncommonly large thing," originally and especially an audacious lie, formed as if from whop (v.) "to beat, overcome." Whopping "large, big, impressive" is attested by 1620s.