Sounds like the Israelis and the Palestinians. The Israelis refuse to
learn Arabic and the Palestinians refuse to learn Hebrew, so they
communicate in English. I saw a news clip of israeli soldiers ordering
Palestinians out of a bunker, and the phrases they were using sounded
like an old gangster movie.

John F. Eldredge wrote:

The various ethnic-Chinese exchange students that
I came to know were from a variety of countries, and a variety of
ethnic sub-categories (my room-mate was Hakka, for example), so they
didn't always share the same dialect of Chinese and sometimes had to
use English to communicate between themselves.