When you play with fire, you either get burned or burn the house down in more ways than one. Especially if you don't know what you're doing.
That's what happened recently to a chemistry teacher who was attempting to show how to do a natural gas test to his students. I emphasize 'attempt' here, because his efforts went horribly wrong. Things got too hot to handle pretty fast and eventually, he set the ceiling on fire, setting off the sprinklers shortly thereafter.
Suffice to say, everyone in the class was soaked and countless gadgets were probably fried in the process. Everyone in attendance was laughing their asses off, but I don't think the prof will be doing much laughing when he's called in to explain what the hell happened in his class...
One lesson I'm sure everyone learned is this: Don't trust your teacher, because they can be idiots, too.