Even though Duke Nukem Forever purposefully overlooks many of the shooter advancements made by Halo and Call of Duty, it does at least acknowledge their existence. It just does so to poke fun of them. Early in Duke Nukem Forever, Duke is offered some green power armor to use when taking on the alien menace in downtown Las Vegas. Naturally, the big guy declines, dismissing power armor as something for, well, "pu----s."
Duke don't need no power armor.
It's a clever little aside and further demonstration that Duke is about machismo above all else in his quest to save his babes and kick alien ass. We'll see if Duke (and Gearbox) have any other video game targets when Duke Nukem Forever drops this May.