Here's what rhymes with whodunnit.
whodunit subunit Words that almost rhyme with whodunnit
rummage scrummage budget punished dunnest russet sunlit nugget junket funnest published druggist unpunished rubbished whatsit fussbudget demist punkest culprit unpolished floodlit drunkest unpublished republished mentalist discomfit troglodyte vulgarest sextuplet