To hit or strike someone hard, or to beat decisively in a competition or game.
A variant spelling and imitation of 'whop,' likely originating from onomatopoeia—the word imitates the sound of a hard blow. Regional American English has used this since the 1800s.
The way we spell 'whup' with that 'wh' actually traces back to Old English, where that 'hw' sound was pronounced differently—that's why 'who' and 'whup' have that unique sound that's disappearing in modern English!
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