You can't trust the quiet ones..!

I was standing in front of the class teaching as usual. At the table of desks in front of me, I notice a loose sheet of paper appear. I am unsure of which learner it belongs to, but before I can make any assessment, one learner quickly snatches the paper, which is followed by the other learners at the table joining in and very quickly grabbing back and forth across the table at the paper. In about 3 seconds, the paper completes 5 or 6 passes. Suddenly, Maria, a petite, quiet, bright girl at the table, manages to, in the blink of an eye: snatch the paper, crumble it, put it in her mouth, and swallow it. And it was gone. It happened so fast, as if these actions were somehow all completed simultaneously. It was all so discrete too, so I was fortunate that my teaching went uninterrupted. Although I suppose there was not much reason for major interruption to occur since what had happened, even if anyone else in the class would have noticed, would not have been perceived as very abnormal. If anything, the interruption would have come from me if I had not managed to cover up my laughter!