Definitely inappropriate...it's hard to give an example, because the actions or words don't seem inappropriate at the time! I never felt this growing up; I suppose my family and friends were just used to how I am. Since graduating from college, though, it's been very difficult for me to make friends. At two of the schools where I've worked, I had a very hard time socializing or even getting along with the other faculty. (I have no trouble bonding with my students, especially my special needs students.)
I am intentionally becoming more quiet, though, as I hate feeling that I have done something wrong, as I never know what it was or how to fix it! I find that I tend to dominate conversations, even without realizing it, so I now make an effort to listen rather than bringing in my own (often long-winded) opinion -- for example, listening to my friend talk about his relationship with his little niece, instead of talking about how wonderful my little nephews are. I really do find what other people say interesting, but I worry that I give them the impression that I don't.
In social situations, I have taught myself to sit quietly with a smile on my face, laugh when everyone else is laughing, and only speak when spoken to (unless I am greeting people). I will offer a compliment if I'm not interrupting someone else's conversation, say on a haircut or particularly sharp outfit. The only person who seems to worry if I'm quiet is my husband, who is used to my habit of talking a lot (and without knowing it, loudly). He thinks I'm not having fun! My goal is to appear thoughtful and not aloof -- that's why all the smiling and laughing -- because I am sick and tired of doing inappropriate things! Since I have so much trouble telling what's inappropriate in a social situation, being quiet seems like a better option! I'd rather be considered "that quiet girl" than "that weirdo" or "that rude girl."