An onomatopoeic sense?

According to the dictionary, whopping (the verb tense) means "pulling or whipping out; beating or striking; defeating totally" [from the Middle English whappen, alt. of wappen to throw violently].

On the other hand, whopping (the adjective) means "extremely large; extraordinary; extravagant".

So, Bobert, have one more whoppin' whoppin' on me, just to keep up the momentum! Ya can't fool me; you ain't gittin' no scrapple YET! Ya got some weeks to go yet, ol' son...