Underclassmen rhymes with:
classmen, classmen, classmen, classmen, craftsmen, marksmen, servicemen, berumen, brakemen, bushmen, cameramen, chairwomen, classmen, craftsmen, dahmen, dohmen, ehmen, forewomen, freemen, frenchmen, hinmen, holmen, kamen, kelemen, kinmen, lemen, lemmen, marksmen, meskimen, midshipmen, policewomen, servicemen, uelmen, vonallmen, watchmen