I never heard of mayo on fries either, till I saw my niece in FL eating them that way just a few years ago. YUK!! However, now my son eats them with mayo too. I don't like mayo anyway, so you'll never see me eating fries with mayo - only ketchup or vinegar. Of course, being from New England, vinegar was the only way I ever ate them until I ventured out into the world, and saw everyone else eating them with ketchup. I thought that was gross too, until I tried it.