Kris Humphries is less than a month away from walking down the aisle with fiancee Kim Kardashian ... but someone needs to teach this mega-tall basketball player something called husband etiquette ASAP.

When someone asks who the hottest woman in the world is ... you better say your fiancee, especially if she's walking with you! Watch his "wrong answer" in the video above.

Oh, Kris ... you better learn quick.