Coupon rhymes with:
anton, arabichon, arabicon, avignon, bygone, cabletron, chemlawn, cinnabon, fair-lawn, fairlawn, kingon, kulon, mahlon, marienbonn, mastodon, regeneron, roselawn, sandon, saskatchewan, schiferon, skylawn, woebegone
Coupon sounds like:
c-span, caban, cabana, cabin, cacophony, caffeine, capano, capen, capon, capone, caponi, capuano, caspian, cauffman, cavan, cavanah, caveman, caven, cavin, chabon, chaffin, chafin, chapin, chapman, chauvin, chavin, cheapen, cheekbone, chiappone, chiffon, chipman, chopin, chovan, cobain, cobaine, coben, cobian, cobin, coffeen, coffin, coffman, coopman, copeman, copen, coppin, coven, coveney, covin, covina, covino, cspan, cuban