Why can't Americans say "sudoku"? Suduku, soduku, sodoko... I've heard 'em all. It's easy. Repeat after me: Sue-Doe-Coo. Sue-Doe-Coo. Good job! Now, tomorrow we'll work on Kakuro.
Mr. Verb suggested that it must be the pervasive vowel harmony of English. I said, that's right, Mr. V, and patted him on the arm. The old darling.