In High School chemistry we did this one experiment that produced this very deadly poison gas.
I don't remember what it was, but when combind with copper the gas was produced. So we're in the classrooms big hud thing that vented the air, and I was holding the tongs that had the pennies on it. The teacher yelled at me because I didn't have my goggles on, so while still holding onto the tongs, I turned around to grab them. Thereby bringing the penny smoking with extremely deadly glasses, right into the faces of the entire class. I had only had it there for a second by the time I realized what I was doing and shoved it back into the vent, but it was probably one of the dumbest things I've ever done.