I had to invoke this trope twice within the same month (November 2010).\\ Once was when talking to someone else (Alice), with another person (Bob) listening in. Alice knew what I was explaining, but Bob did not. It was Bob's duty to be aware of this information, and to be {{MrExposition}} on that subject. {{AsYouKnow}} let me remedy his knowledge gap without impolitely hinting that I knew Bob had messed up.\\ Not that this stopped Bob from "forgetting" critical information - including part of what I had explained to Alice in front of Bob. Not one week later, I used this while talking to Bob directly. I said "{{AsYouKnow}}...", while my exact thought was, "{{AsYouKnow}}, but I do not trust you to have remembered..."\\ As of this writing, it is December 2010. Suffice it to say, I do not expect to ever see Bob again.

I had to use it in my story--to a rather comedic effect--as the main character refuses to call the captain of the ship she's on anything but Captain... even after they start dating.

My wife serves as Mrs. Exposition a lot. I forget things easily.