Whopping rhymes with:
swapping, wapping, chopping, copping, cropping, dropping, flopping, hopping, lopping, mopping, popping, propping, shopping, sopping, stopping, swapping, topping, wapping
Whopping sounds like:
waiving, wapping, waving, weapon's, weapons, weapons', weaving, weavings, webbing, weeping, whipping, whooping, wiping