Have you ever had a mean, dumb, or inappropriate thought that was meant to stay inside your brain that you accidentally said out loud?
If you answered "no," then you are patently untrustworthy. All of us have put our foot in it at some point, it's just a matter of how bad it got, and whether other people noticed and reacted to our faux pas.
Cheerfully singing my pin number as I'm at the cash machine.
I worked in a building that required me to check into the front desk to get the keys to open my area of the building. The front desk clerk this day was a young black guy. He happened to share my uncommon last name. So he says, "I wonder if we are related?" and I respond with, "damn, we could be related through slavery." We stare at each other blank-faced. I just sigh and say "f*ck man" and he just laughs. We had a good rapport for the rest of my employment there, but still I look back and think, "what the f*ck brain?"
I'm white for the sake of the confused.