"I don't want to hear you speak French. If you don't want to be here, that's fine - I'll tell your professor not to send you next time. But, maybe the reason you don't understand English is because you sit in all your classes, speak French, and don't try. If you don't want to speak English, that's fine, but then I don't want to hear you speak at all."
I went on like this for a couple of minutes...the other students were totally backing me up, too, which was pretty awesome. I think he felt bad, because he actually shutup for the rest of the class period.
It was really strange to confront somebody like this in the middle of the class, and I was actually really scared the whole time (but I don't think it showed). It was something that was outside of my comfort zone, although necessary since I had begun to lose control of the class and he was acting as the ring-leader.
I ended up having about 10 minutes at the end of class and nothing to do, so I put this picture of Will and Joe dressed as hobbits from a beer pong tournament last year up on my computer, and asked the students to imagine and describe what was happening:
I should have been able to predict that they would say nothing - I reacted quickly when they didn't, though. I made them all take out pen and paper and write "Who? What? When? Where? Why?" on the board. I told them they had 5 minutes to make up answers to the questions, write their names on the papers, and turn them into me as they left. (Here are my favorite answers: (1) "There is two man, they drink and do the fiesta. It the party of village in winter. They do a grimaces in the picture." (2) "This is your friends in bar in your country. They drink and make a party. In winter because they have a blouson. They make a grimaces in your pictures. They dancing, they have a eyes brow, they are funny. Because it's nice. They wear the cape.") This exercise accomplished a few things -- first, it filled the last 10 minutes of class really easily. Second, it allowed me to stop talking and made them start working. Third, it showed them that, if I wanted, I could have the power to affect their grades (even though I don't think I actually do). Fourth, it allowed me to get the name of the little jerk so that I can tattle to his teacher.
Situations like this show me not only that I'm not meant to be a teacher (I guarantee I know many, many people who would handle situations like this, and far more difficult situations, with a much higher level of grace, composure, and effectiveness), but they also are good lessons in learning how to think and react both quickly and effectively. I'm not sure if I fully succeeded this time; we shall see.
Immediately following that class, I was supposed to have another group of the same age. Luckily, the group couldn't come because their professor was being observed, so I ended up with a group of 11-year olds who were absolutely adorable. They loved being in the classroom, and I had so much fun with them!