Many stores here indicate closing time by playing Auld Lang Syne. My grocery store closes at 8, and I was just there, so I got to hear the lovely tune.
Of course, it got stuck in my head.
So, I walked into my apartment, closed the door, and burst forth with a resounding "For Auld Lang Syne, my dear!"
And that's when I heard the outer door of the building. My apartment is right by the door and has very good acoustics. I only hope that was my neighbor coming in! If he was going out, he just got a free concert!