The appeal that attracts Jewish men to non-Jewish women. This can be reasonably explained by the fact that on average the typical non-Jewish woman is hotter than the typical Jewish woman. Another explanation is that there is an unexplained 'force' that drives Jewish men to find non-Jewish women more attractive even if they are objectively just as attractive as a Jewish girl.
David: Hmm, I think that Sara and Christine are both 7's.
Woody: Ya, but Christine is hotter, and I don't know why.
David: It's cause Christine's got mad shiksa appeal.