In the past two months I have found myself in two situations that are hard for me. First, being with an individual person who pushes ALL my Aspie buttons (not maliciously, no blame here), and makes it very, very hard for me to handle. Second, large groups of people most of whom I don't know. I've managed to get through these experiences in the moment unscathed, though of course I was tired and frustrated and angry and it took me hours to rebalance myself after the fact. That's par for the course of being an Aspie, you can't avoid it, so you have to just deal. In the process though, I have learned three HUGE coping skills that will not only help you get through but will help ensure you don't act in a way that is rude, or hurt anyone's feelings.
A) If you feel the meltdown coming, if your buttons are pushed and you have to fight to keep your mouth shut for politeness sake, when your body starts to tremble and you can't make eye contact anymore, the best thing to do is simply GET OUT. Don't try to fight the breakdown or the anger or the words stopped up in your throat, you won't win the battle and it will wear you to the bone trying. Make an excuse and get out. Don't be rude, but do be hasty, or you risk saying the wrong thing. People that know you are an Aspie will recognize and accept this. If they don't, hopefully you've covered yourself well enough and if you haven't, there is only so much you can do. Because getting out, getting alone, getting into an activity that relaxes you, is the only thing you can do in this situation.
B) One of my peculiarities as an Aspie is figuring out how to not talk too much, not dominate the conversation, not say every little thing going on in my brain because it is interesting to me and I assume it is interesting to other people. The simple solution to that is to ASK A QUESTION. Ask a question preferably with a long answer. Get someone talking, it takes much of the burden and weight off of you. If you have a hard time talking, you don't have to talk! If you have a hard time not talking too much, make them talk a lot first, and you are good! Plus it shows the other person that you care and that you are really listening, which you ARE (or at least I always am). It's a win-win.
C) At some point or other we are all going to have to be with a large group of people, and people we don't know, and conversation. When you can't follow the conversation, when the noise is too much, when you are upset about something, when you aren't in a bad enough state to have to get out but you just have to zone out for a while, the easiest way to do this is simply to stop talking. You can glance around at the speaker so they think you are listening, you can even listen if you choose, but if you don't talk you can fade into the woodwork until you get a grip. Also, not talking precludes the possibility of saying the wrong thing or being rude or looking stupid. Silence in these situations is always an OK thing. If it gets too bad, go back to A).
Hope this helps!