I Know Exactly What You Are Talking About...

One of my professor told us that she wants to learn one sentence in each language (of the countries she visits)...

"I know exactly what you are talking about. "

So whenever native people start talking in their own language then she can just turn to them and try just saying this specific sentence to them and see their expressions.

However now the question is: do we know what they are talking about? Or in some cases, do we know what we are talking about?
Being like minded with someone is a blessing in disguise.... Cherish it...