I learned this one growing up in Texas and, subsequently, living in Los Angeles: always use the 'usted' form when speaking to a Spanish official. Mexican border patrol cops don't like it when you call them 'amigo,' give them a hardy pat on the back, slip a $20 in their pocket. No bueno, it doesn't fly. By the way, those of you not laughing at that obviously took French in high school, and that was a gay choice.
I was in New York last Christmas - it's snowing; there's a guy in a t-shirt. I'm like, 'Dude, aren't you cold?' 'No, I'm from New York. I don't get cold.' Just 'cause you're from a cold place doesn't mean you're genetically predisposed to not feeling cold. You're not a penguin. I was like, 'In fact, sir, you're Puerto Rican, so if anything, you should be more cold.