Lumper's rhymes with:
bumpers, jumpers, bumpers, campers, dampers, hampers, jumpers, kemper's, pampers, samper's, shrimpers, smokejumpers, swampers, tempers
Lumper's sounds like:
lamberg, lambros, lampreys, lampros, lemberg, lemburg, limberg, limbers, limbrick, limburg, lowenberg, lumberjack, lunberg, lunenberg