Term most likely dates back to the Philippine-American War (~1900) and has been used against a wide range of peoples, usually Asians but occasionally Europeans and even the English. Unknown origins, possibly "goo-goo," from the Tagalog language (a major language spoken in the Philippines). Although many have it originating in Korea either by referring Korea's original name, "Hanguk", or during the Korean War when Koreans would ask American GI's "Mi Guk?" ("American?" in Korean) which sounded like they were saying "Me gook." Was soon adopted for use in the Vietnam War. Technically this should only apply to Koreans, but the Vietnam War made it most popular when applied towards the Vietnamese.