Boombox rhymes with:
breadbox, fischbach's, gearbox, icebox, jukebox, mailbox, matchbox, saltbox, sandbox, skybox, soapbox, tarbox, tinderbox
Boombox sounds like:
bambach, banpais, baumbach, biamby's, bimbos, bomb's, bombay's, bombeck, bombs, bonifacio, bonifas, bonobos, boomboxes, bumbaugh, bumpas, bumpass, bumps, bumpus