I have this happen quite often, actually, because my brain is sarcastic and quick to tell my mouth to speak, I have to fight it. Because it's really, really not appropriate in most cases to tell people what I'm really thinking.
However, today I wish I hadn't fought so hard.
I was at lunch with my 2 youngest kiddos. I walked up to re-fill my drink, and this guy approaches the drink station, take-out bag in hand. He had just been waited on, and I can only guess that it was less than satisfactory. It also has bearing on the story that one of the girls behind the counter was new (training) and English was not her native language. She was perfectly pleasant, though, and not even very slow. However, it was clearly not fast/fluent/whatever enough for this guy, because what he said to me when he walked up next to me was, "I guess NOBODY speaks friggin' English anymore."
The response that had my mouth CLAMPED shut was, "Well, it's a good thing for you most people speak 'asshole'." Honestly, the only reason I didn't say it out loud was because my kids were right there and Jon was on duty and I didn't want them to have to witness their father being called to the scene of a brawl in the McDonald's lobby with his wife as a participant. It was all very Jerry Springer in my head.
But since this is MY blog, now it's in your head, too. Sorry for the profanity. (Not really.)