Jewish Anglo-Saxon Protestant. Used by some Jews in Northern California to describe people of Jewish heritage who have completely assimilated into white gentile culture to the point that they are indistinguishable from WASPs, or people who seem like WASPs but are Jewish or half-Jewish. The term probably had its roots in the early 20th century when Eastern European Jewish immigrants to the U.S. resented the more assimilated, wealthier, more established American Jews of German and Austrian origin, thus making it the opposite of kike. The term is rarely used outside of the Bay Area and its use seems to be dying out given the almost total assimilation of American Jewry, particularly in the West.
He seems so goyish, but he's really a jasper.