I keep learning again and again, apparently to little effect, that one should not assume what others know about. I was just asked "what does LOL mean?", because I had used it as only answer to a point in an email.
The point being that I was asked by a man who has used the Internet daily for fifteen years.
And he is intelligent and very successful, and speaks English well. Apparently he just never before has seen it used in a context where he felt compelled to query about the meaning.