Noun

1. An organised practice to prepare occupants of an office, school or other public building for evacuation in the event of a fire.
2. any pointless, unproductive, useless, or chaotic activity (sometimes Chinese fire drill, but this usage is becoming outmoded in an age of political correctness)

   Since they changed the standards again, our previous efforts now just amount to a fire drill.

3. any chaotic, unexpected activity. (With the dropping of Chinese the phrase has also often lost its pejorative meaning of pointless and unproductive. In this way, fire drill is often used in the same idiomatic way putting out fires or fire fighting is used.)

   Sorry I didn't get back to you earlier, I've been involved in a fire drill all afternoon.