I actually feel relieved and elated in these situations. It always takes a while for me to become a functioning part of a group, so when I get there, it feels like a big achievement. People in the group still see me as weird (or weird and original), but you can't have it all... That's when I stop trying and consciously working on building the relationship and just show more of my real self, but by that time some of them already like me as I am.
No need to say that it cost me years of learning about socially accepted things and behaviour rules and having all kinds of unpleasant thoughts about myself.
With my family I don't really need to pretend, just recently I had to spend some time with them after a long break, and I was really shocked to see how stronger my AS traits got when they were around.