You may have heard before that for people of Asian origin it is very difficult to pronounce the letter "r", as they don't have that sound in their languages. This is not only an issue with Asian languages, as any student of French, Spanish or English will tell you, with the problems with nasal vowels, rolled r's or long o's.
One of the funniest examples I have found is with that beloved language of mine: Finnish. Letters such as c, d, b, f, g or z cause problems to Finnish speakers, as they don't come naturally in their language (which uses the stronger sounds of k,t, p, v, k, or s instead), even though they have other frontal vowel sounds written with the letters ä, ö, y and å that might easily perplex foreign students.
This is shown when a Finn is learning Spanish, for example. Even though the pronunciation of both languages in general is very similar, a Finn might end up singing "Pésame mucho" instead of "Bésame mucho" (roughly translated to "it weighs a lot" or "I'm so, so sorry" instead of "kiss me repeatedly"). Hilarity might ensue.