Nighthawks rhymes with:
blackhawk's, blackhawks, echohawk's, mohawks, seahawks, skyhawks, tomahawks, airlocks, blackhawk's, blackhawks, boardwalks, cornstalks, echohawk's, gamecocks, goldilocks, hydrox, mohawks, seahawks, sidewalks, skyhawks, tomahawks, toolbox
Nighthawks sounds like:
nacogdoches, nasdaq, nasdaq's, nast's, nastasi, naugatuck, necessitates, necessities, neckties, negates, negotiates, nest-egg, nests, newscasts, newsday's, next's, niceties, night's, nighthawk, nights, nights', nonjets, nonstick, nugget's, nuggets