Clay (the director) had his face in the music for the first 5-10 seconds of the first song, and when he looked up, the expression on his face was priceless. There we all were, some wearing everyday sunglasses, and some who managed to find novelty ones in wacky colors for the occasion, looking straight at him smiling and singing. If he knew in advance that we were going to do it, it didn't show. Of course, even if he had known, I doubt he would have been prepared for just how silly we looked!
It got even better when the soloist came out and handed him a pair of his own. He didn't put them on at first, but (I'm guessing) once the music got easier, he put them on and wore them for the rest of the number.
It was definitely one of my favorite moments of the entire 2009 show.