derogatory for "Italian," 1912, American English slang, apparently from southern Italian dialect guappo "dandy, dude, stud," a greeting among male Neapolitans, said to be from Spanish guapo "bold, dandy," which is from Latin vappa "sour wine," also "worthless fellow;" related to vapidus (see vapid). It is probably not an acronym, and the usual story that it is one seems to date only to c. 1985.