Japanese, despite being an extremely difficult language, at least for me, I find it incredibly fascinating and I'd love to know it. 

Someithnig extraterrestrial, probably.

Or the language of crows. The latter i can try to decipher myself of course...

Another option is to make a dog or a cat speak... well, here I have to consider 'speak what'.

Korean....then French. If my genie was nice he would grant me two wishes. My genie would understand that I've been trying to learn French since I was 10 yrs old and just can't grasp it. He would have pity on my and say "wish granted, you poor little girl". Then becuase he loves me so much, he would grant my wish to also be fluent in Korean, because I can speak to my friends and watch my Kdramas w/o subtitles. Yes, my genie is the best!! LOL. 

French

"Other"