I was reading The User Pool like I tend to do (and you should too, 0 readers, it's awesome-o), and I read about how he burned to death in a pretend fire drill. In the beginning, he talks about how he never believes in fire drills because he know that when a real fire breaks out all hell is going to break loose, no matter how much you cut into company productivity to practice "drills". Anyway, he got me thinking: I know that what he's saying is true, you know what he's saying is true, and anyone who's ever been in an office during an actual fire knows this is true, so why do they practice?
And then I got it - to make them mindless slaves to the fire alarm.
Think about it: if you practice a drill every month for 20 years or so and a fire does break out (and you don't see it, this is critical), when the alarm goes off you're probably just going to think "oh great, another drill" and trudge out of there without pushing any old ladies down any flights of stairs or trampling the people in the red vests. Thus any panic and mosh-pit-like deaths are avoided because you've been trained like one of Pavlov's dachsunds (I doubt he actually used dachsunds, but I like the imagery) to groan frustratedly and trudge outside at the sound of the alarm.
However, this is all dependent on nobody seeing the fire, because when they do they will panic and tell everyone it's a real fire, which will cause everyone else to panic and the guy in the red vest and fireman's helmet to get a size 12 footprint on his face.