If you walk into a high school where you know no one, find the toughest looking girl in the halls and tell her she's ugly, them's fighting words. Or bellicose ones. Bellicose means eager for war.
Bellicose is from Latin bellum "war." A near synonym is belligerent, from the same Latin noun. You may wonder if they're connected to the Latin bellus "pretty, handsome," which gives us the names Bella or Isabella, as well as belle "a beautiful woman." They're not. War and beauty are not related, except in the case of Helen of Troy.