Here's what rhymes with butthough.
bo doe dough po toe tow beau jo beaux cho dau doh no so know go though low show ago co blow pro row tho fo foe ho lo audio mo ro wo woe patio yo bio ceux faut goe hoe ko propos sew soe tableau uno vo mow noe roe sho tableaux topos tuo yeux zo bro chateaux dunno rho stow trow chapeau kapok turbot whoa bandeau chapeaux below flow grow slow snow throw glow plateau quo bestow fro chateau crow hello thro aglow apropos dicho floe plateaux throe sloe tarot gateau kayo matzoh fatso gateaux pekoe borzoi schmo schmoe although radio studio undergo buffalo indigo dynamo nouveau polio vertigo aliquot cameo domino outgrow rodeo spatio trousseau adagio oleo piccolo undertow deathblow pompano trousseaux tallyho resew ratio embryo folio portico stereo bungalow calico forego forgo politico escrow medico mistletoe siglo afterglow pistachio foreknow regrow romeo overthrow overflow presidio oregano overgrow mustachio microdot moustachio portfolio braggadocio pianissimo archipelago impresario generalissimo