Seinfeld where George’s dad translates the insults directed at Elaine, and runs into his old girlfriend. Then he tries the stop-short-and-grab, and she says she’s not that kind of girl. 
I think it depends on the person. My wife has almost native fluency in English but her native language is Russian. She has another friend of the same ethnic persuasion who also speaks English perfectly. They still invariably speak to each other in Russian especially if no one is around or paying attention to them. At this point, it is a question of habit.
I always speak Portuguese with my dad, and when someone else is around, we will switch to English but it always seems slightly unnatural and it always feels funny.
English-only rule?!
As I understand Gfactor’s legal advice, that means if I’m posting from work, I can sue!
And, because these discussions always have plenty of “but in MY experience” comments , I recently got a pretty good haircut in a style I wouldn’t have considered when the stylist reached the limit of her English comfort zone when she pointed at a picture and asked, “Like that?”
A little off topic, but in casinos, dealers and players are only allowed to speak English.
The labs where I used to work had a lot of Chinese speakers, and they would speak Chinese socially and occasionally for work-related things.
Socially, I never minded. If they were speaking Chinese and hadn’t noticed me there and I wanted to join into a conversation, I’d simply ask what they were talking about, and they’d switch to include me, never a problem. For the work-related things, they’d only do it when dealing with complex problems that needed solving - it was easier to be 100% clear right away rather than risk lost-in-translation mistakes, but that was pretty much only if they were talking one-on-one, or the odd sentence tossed in for clarity.
Frankly, even if they were talking about me behind my back, who cares? If they have a problem with me, but don’t want to tell me what it is so I can try and fix it if possible, then it’s their problem, not mine. I’m not going to stress about it.
Of course, in groups/team work, meetings, company communication, etc I’d expect a common language (or languages) to be used. At my old place it was English, where I work now both English and French are fine (though French is preferred of course… this is Québec!)
I also tried (but failed miserably!) to pick up a few words in Chinese. I learned a lot about their culture and traditions and really enjoyed working with them.
Based on my experience of workplace conversations… if any manager of any company assumes that alot of what is said by any employee in any language consists of “complaining about other workers, the job, and management” they won’t be to far from the truth 
Oh yeah! I remember that one too. Doesn’t Frank meet his Korean war girlfriend?
King of the Hill must have stolen the joke. Hank’s shin-less dad goes to the salon with Peggy, since she’s sure the employees are making fun of her huge feet. And they are.
The court system in Wales grants a specific right to any party to use Welsh (rather than English) if that’s the preference.
You may need to give notice so that translators can be arranged, but it’s illegal to refuse someone the right so conduct any part of their case in Welsh.