Spiel, kosher, ganof and matzoth are examples; their vowels remain un-American.    From Wordnik.com.  [Chapter 9. The Common Speech. 10. Vulgar Pronunciation] Reference

I should worry, 76 In its way, is correct English, but in essence it is as completely Yiddish as kosher, ganof, schadchen, oi-yoi, or mazuma.    From Wordnik.com.  [Chapter 6. Tendencies in American. 4. Foreign Influences Today] Reference