I had a student that used to do this to me. At first, he'd point at me and I'd play along and put my hands up in surrender and he'd laugh. Then, he took it a step farther over the course of another 3 classes or so, and started to constantly shoot me. Well, it got to be a real distraction and his laugh became a bit maniacal for my liking. Finally, it got to the point where as soon as I would click start and open my camera, he'd be there waiting with the gun pointed right up to the camera and he would pretend over and over that is was shooting himself in the head (the straw). So, I decided to get the parent involved after about 6 classes of this behavior. I thought maybe the parent wouldn't respond and the gun would just dissapear. However, the mom did me one better and sent me about a 3 sentence response to why she thought his behavior with the gun and mimmicking suicide was also completely unacceptable by her in her house. So, I just blissfully pictured the student getting the brakes beat off of his rear-end (a proper spanking and not a beating) for acting like a little maniac.