Duke Nukem is a character from the video games of the same name. He has a notable appearance in the StrikeForce Kitty series.
StrikeForce Kitty: Last Stand
This costume can be obtained by defeating a random raccoon wearing the same costume. Once successfully acquired, it can be found on one of the hangers of the "Ranged" category.
StrikeForce Kitty League
Duke Nukem, like many costume sets in previous games, appears by chance in the main menu of StrikeForce Kitty League, worn by either the cat or the raccoon who are fighting in an "arena". However, this costume is unobtainable in gameplay.