I'm ashamed to admit that I speak basically no Spanish, living as I do in a town where the phonebook has 74 entries under “Chavez” and only 14 under “Jones.”
Frequently, people call me on the phone and speak Spanish. So that I could be polite to them, I asked a Spanish-speaking friend of mine to teach me how to say “I don't speak Spanish.” I studied on it for several minutes until I was confident I could pronounce it correctly.
However, when I used this phrase to answer phone calls in Spanish, I could never get anyone to believe me. They would continue in Spanish, and I would repeat my magic phrase “No hablo Español,” and they would go on in Spanish, and a good time was had by none.
One day it occurred to me that maybe I was doing too good a job pronouncing it. Next time I got into this situation, I used a horribly exaggerated Texas accent: “No-oo HOB-low ess-puh-NOLE.”
That did the trick. Since then, every Spanish-speaking caller has believed me right away.