To ujm: I have always believed that the term “JAP,” when referring to a Jewish woman, is offensive for a number of reasons. First of all, it is also a word used during World War II to refer to one of America’s enemies, and it was generally meant to be offensive to all Japanese, including Japanese Americans put into American concentration camps.
More generally, it sterotypes Jewish women and adolescents as privileged and spoiled. Some of them are, many are not, but “JAP” smears them all. If you and/or your acquaintances use “JAP” as often as your post implies, you are doing a disservice to Jewish women.
I once heard a Reform rabbi speak extensively about the wrongness of the term “JAP”, so, evidently, the Reform Jews get it, even if holy Jews like you do not.
“JAP” is, among other things, loshon hara.