That reminds me of an acting class I took once where we had to do an exercise where we made an "impassioned speech." This one woman was able to do that in English, but when she had to do something similar where she was speaking to her parents she had a lot of trouble and finally asked if she could do it in Spanish (I think it was Spanish that was her native language at least...now I can't remember). Made sense, and even if you couldn't understand what she was saying from an acting standpoint you could still tell it did the trick. You could tell she was impassioned!

Things like humor would definitely work that way, I'd think, and I can definitely see how certain words would just always give you trouble if you weren't brought up with them. I met a guy once whose grandmother had named her two cats after two words in English she couldn't grasp the meaning of just that way. I think they were something like, "Likely" and "Definitely." LOL! It's especially interesting when somebody speaks the language well--like, I knew a guy who was Polish but when I met him I didn't realize it.

See, it really does sometimes seem like a person has a slightly different personality depending on what language they're speaking, if they are fluent. I know I've felt so frustrated trying to communicate in a language I can't speak--it's like a character in a book I read once said, "In English I am stupid boy. In Polish I am not stupid." You can know, intellectually, that the person really is smart but they can't communicate it.