Don't know what something means? That is fine, and good.
See it as an opportunity to grow and expand.
Simply saying that you don't know and then stopping signifies an unwillingness to change, to evolve as a person, surely?
We all encounter things every day that we don't understand or don't know about.
Expand your horizons.
Dare to grow, to change.
Don't just talk.
"I do not enlighten those who are not eager to learn, nor arouse those who are not quick to give an explanation themselves.
If I have presented one corner of the square and they cannot come back to me with the other three, I should not go over the points again."
See this as a friendly challenge. An invitation to broaden yourself?