Showboat's rhymes with:
ferryboats, gunboats, houseboats, lifeboats, riverboat's, riverboats, sailboats, speedboats, steamboats, tugboats
Showboat's sounds like:
sabatka, sabbaths, sabotage, safeties, safety's, savidge, savitch, savitsky, savitz, seafoods, septic, shafts, shifts, sifts, skeptic, skeptics, sobotka, sociopaths, softech, softkey, sovetskaya, soviet's, soviets, soviets', sovyetsky, spades, spates, spats, spatz, speeds, spits, spitz, spots, spotts, spouts, spud's, spuds, svitak, swift's, swifts