Digression-
It's Italian. Guappo (pronounced gwappo or woppo) means bold, showy, but also took the meaning of ruffian. The word came to North America with Italian immigrants.
In New York, a group of criminal young men, foreigners and mostly Italian, were known as Waps, Jackos, etc. (1912, in Train, "Courts, Criminals, and Camorra," p. 232). This, and the novel by Wodehouse (1914), in which one of the characters said, "He's a wop, kid. A dago. An Italian."
Often quoted is one from George Bernard Shaw- "What they call an American is only a wop pretending to be a pilgrim father. He is no more Uncle Jonathan than you are John Bull."
Probably from Latin, since it is guapo in Spanish and is found in other latinate languages. Also means a foreigner in Latin America, as well as handsome.
OED

I remember the Italian restaurant in my home town. The menu listed "Wop salad," which my mother often ordered. It varied according to the ingredients the Italian owner could find, but was always large enough for two. With one of his soups, it was a meal.