People insist on inventing new pronunciations for this word, god knows why. I bet you could find entire regions in which the predominant pronunciation of this word is kway-sa-dilya. "Can I get one kway-sa-dilya, and a side of ranch dressing, please?" To be sure, quesadilla is what linguists call a "loan" or "borrowed" word. In most cases, borrowings are modified so that they conform to the pronunciation rules of the new language, but there's something especially insulting about mispronouncing a word as seemingly widespread as quesadilla. I would feel way more sympathetic to someone who stumbles through "smoked trout nicoise salad with hearts of romaine and dijon viniagrette" than a word that is on the goddam Taco Bell menu. The truly mysterious thing is that the people who mispronounce "quesadilla" are inevitably people who look like they probably know the Taco Bell menu by heart. I can see why people are inclined to say "kweh-sa" or "kway-sa," because "qu" is "kwa" in words like "quiet" or "question." And I can understand why people of French-Canadian descent may be inclined to pronounce the "qu" as "ka" or "keh." I guess I can also understand saying "dilla" as "dilya" or "dillah" rather than "diya," but I'm relatively sure that these same people pronounce "tortilla" correctly. But maybe they don't. Maybe they say "tortilya." When you string all of the mispronunciations together, and you get things like kway-sa-dilya, or kah-sa-dillah, it just makes you sad for the state of civilization, for the future of language, for the likelihood that things that matter will be further eroded by people who simply don't pay attention. On the other hand, it's also a perfect example of people voting with their feet, or their mouths as the case may be. Which is interesting yet terrifying, as always.