I've got this thing for origins of languages and meanings. "Oy Vay" or "Hoy Vay" are both correct, and it is Yiddish, not Spanish, basicially meaning "Good Grief", but has a few more derogatory meanings as well. So there, you're both right! One thing to keep in mind that Yiddish, like Arabic, is not derived from same written alphabet as what we use, therefore, when translated in to English the spelling comes out in different ways.