At work, when "were" talking in group(i don't even say a word), people keep asking me why don't i talk & stuff like that and i always say i don't know.I never know if i should answer because they can start saying more about me and not be comprehensible.
Just tell them that you think you are smarter than the rest of them and that you would rather appear aloof and withdrawn than risk saying something that would damage your ego.
Tell them that while they are all allowed to say stupid things that don't always make sense, you live by a higher standard of perfection which keeps you from saying anything at meetings.
If you would like to make light of the situation you could say that you would rather remain quiet and be thought of as a fool than to open your mouth and confirm it.
Sometimes to me it seems the more quiet you are, the more people are interested in you. I'm like this too around people I don't know, I just play it off as being the "strong, quiet type". 8)