In order for this to truly look like an actual kebab, the final member of the group should have some sort of skin-toned phallic object (a dildo, for example) visibly sticking out of his ass. Think about it; wouldn't it look like a very long sex toy is penetrating a long line of gay men through their asses, just as how a long toothpick skewers a long line of food items in an edible kebab?
In order to add more originality to the kebab, the men taking part in the formation could try to distinguish themselves from one another. For example, the men can make different poses in order to appear as the different "ingredients" of a kebab. Also, an alternating pattern of Asian and Caucasian participants would surely add variety to this array of succulent hunks. Hell, you can even throw in the occasional hermaphrodite to really spice up the rack!
All in all, the purpose of doing this is to be creative and have fun.
NOTE: A similar formation, consisting of women wearing strap-ons in order to perform this act, is called a "Lez Kebab." Likewise, a mixture of men and women taking part in this arrangement is called an "Androgybab."