Foot-in-mouth syndrome (not to be confused with hand/foot/mouth disease) is something I suffer from. It is a life long disease causing a person to figuratively put their foot in their mouth. To say some things you probably shouldn't have said in certain company. Word vomit. It happens to the best of us, unfortunately.
One time I called my aunt fat, right in front of my uncle. Not that she isn't overweight, and not that I said it in such a bad way, but it was something I wouldn't have wanted her to know I said about her. Whoops.
Another time, I was hanging out with my roommate and two of his friends (who were roommates with each other). One of the guys was moving in with us, breaking his lease with his roommate, because our rent was better. So I casually asked him when he was planning on moving (I had some things in the closet that I needed to get out) in front of everyone and didn't think a thing of it. Later, my roommate informed me that he hadn't told his current roommate of his intentions yet, and I just spilled the beans. Whoops.
I'm also guilty of talking about something I did with my ex (watched a certain movie, or went to a certain restaurant) thinking I went to that place with my current boyfriend. I think we're all guilty of that one, along with calling our new boyfriends our ex's name. And if you haven't, well lucky you. Thankfully the wrong name thing has never happened with Derek.
Or have you ever had a friend tell you something that they didn't exactly say was a secret? That's happened to me on more than one occasion, and I brought it up in other company only to have them give me major side eyes, indicating I just made a boo boo and shared their "secret." Whoops.
As I said, it happens to everyone. Some worse than others, but i think it is unavoidable nonetheless.