Do you speak English?

I was in the office doing some administrative tasks yesterday when a couple in their 20s walked in and approached Young Secretary's desk. The man started speaking to YS in the language of the-country-that-won't-be-named about lessons for his girlfriend in that language (our school teaches several languages). Of course, YS responded to him in that language (her native language) and then the man translated that info into English for his girlfriend. YS continued on in the language of the-country-that-won't-be-named and I said, 'YS, switch to English.' She gave me a cold glare and then switched to English.

This has happened on more than one occasion in our office. Both Old Secretary and YS speak English very well (YS has been mistaken for a native speaker (by native speakers) on more than one occasion). Common sense says that if three people are speaking together and one doesn't speak the language of the other two, but all three speak English, one would switch to the language they all have in common so that they could all participate in the conversation.

Common sense is definitely lacking where I work.