Difficult Foreign Sounds

What foreign sounds are you proud to have mastered? Which ones are you having difficulty with?

I learned how to make a Japanese R/L sound. It took me longer, but I also learned how to make a French R sound. Weird sounds in French, like the sound U makes, aren't bad for me.

Most of what is hard for me are Rs. I've been trying to get a Russian or even Spanish R, and I just haven't been able to make those sounds. I also can't make the German or Scottish ACH sound. That one would probably just take more practice, though.

>>5
Different poster here. American English is my mother language, but not only can I not easily pronounce any of the th sounds, I cannot "hear" them either. I usually hear them as "f" in words like teeth, and "d" in words like they. I also hear it as "v" in weather/feather.
I believe it may have something to do with having Russian parents.