It is a struggle. Honestly, my kids "out" themselves most of the time and people comment on something they said or did which usually seems like no big deal to me. I can't hide the way my DD4 communicates, her vocabulary, etc. She may pick something up and read it or showcase her memory etc. People actually seem to notice how smart my 26 month old is and I guess I just take what she does for granted since this is all I know.
I usually don't say much, but every once in awhile things slip and it hasn't ruined any friendships that I know of so far. I think it depends on the moms. For the most part, I just let the kids hang out and play and if they do something the causes people to comment, I just roll with it.