Do you know what this is?

I was teaching a grade 9 class the grammar point "Do you know what this is?" I had made a handout with a bunch of Canadian type things on it, and they were supposed to go around and ask their friends if they knew what the pictures represented. One of the, how should I put this, "less motivated" students started walking toward me. I had a feeling he was going to do something sketchy, because he had the typical smirk on his face like he had thought of something super clever and could barely keep it inside himself. So to my surprise, he started asking the correct question, but the sheet was rolled up in his hands. I told him to use the sheet, but he ignored me of course, and then said "Do you know what THIS is?" As he said "this" he pointed, of course, to his crotch. To be honest, I was actually kind of impressed, because he used the grammar I was teaching in a way that made sense and it showed that he really understood what it meant. Nice.