kike

Originally used by German-American Jews as a slur for Eastern European Jews immigrating to the United States. The most dominant theory is from Yiddish קײַקל (kaykl, “circle”). In the early 20th century, non-English-speaking Jews that immigrated to the United States would sign papers with a circle as opposed to a more common X, in order to avoid using a symbol reminiscent of a Christian Cross. If so, a doublet of chakra, chakram, charkha, chukker, cycle, cyclus, and wheel. Other theories also exist, in particular a contraction from the documented phrase “Ikey-Kikey”, an American-origin reduplication of ikey, which in turn is a British-English pejorative for Jews after the prevalence of the name Isaac. Alternatively, from Scots keek (“to peek or peep surreptitiously”), used in the New York City clothing industry to refer to the practice of sending spies to work in competing garment factories to copy designs which would then be reproduced and sold at lower cost. Eastern European Jews played a major role in the clothing industry and were perceived to frequently participate in underhanded business tactics. Originally mostly used by older, established German Jews to refer to the Eastern European newcomers, eventually it became generalized to all Jews.

来源：wiktionary