How do you use - 我还是做一枚安静的N 吧
Its a funny way of describing "I'll remain a spectator and not get involved in the matter", because "I'll never reach that level" or "I'll never do such a thing/achieve such a result". 

You can definitely say "我还是做一枚安静的老外吧。" or replace it with any other nouns, but it depends on what the situation is. For example, if you see a Chinese guy doing something that you'll be never able to do, you can say "我还是做一枚安静的老外吧。" meaning you are amazed by the situation and will remain a foreigner and not try to achieve what he did...It's just a funny way of saying things.

It all comes from this saying "我只想做个安静的美男子(I only want to be a silent/low profile handsome guy" if you want to look more into it.