I can curse fluently and pick up a hooker in Korean. Thanks to Uncle Sam. Not that I ever did such a thing when I was stationed there, but I watched others do it.
All I thought about in my off duty time was Moms apple pie, Baseball, and how could I help my Sgt..
That's my story and I'm stickin with it!
I strongly advise parents to encourage their children to learn a foreign language at the earliest age possible. Many schools give mini-courses in Spanish, French, German and Latin, and then the child can choose in middle school and high school what language to pursue. Foreign language study develops mental facility and fluency of expression in the student's own native language also.
I can pick up a hooker in any language you name.