One of the favorite stories is about the first time I took my wife to England. She majored in British literature in college and is the type of person who reads Shakespeare for fun, and can even read and speaks middle English. I worked and traveled to England a few times a year and had lived there in my early 20s, before we met.
For our fifth anniversary I took her to England. It was her first time ever leaving the US. In fact the first time she left the southern US.
We're standing at the curb at Gatwick waiting for a cab and there are two guys behind us talking. My wife leans over and whispers, "what language are they speaking?"
I just started laughing, and explained they were speaking English, they are just Scottish. All that book learning and studying of the language couldn't prepare her for the Scottish accent.