I used to work at a large department store chain. One day after I had just clocked in, I noticed several of the customers entering the store began coughing violently and the front end manager began complaining of headaches. I paid no mind to any of this and headed to the back of the store. Five minutes later they called for an evacuation of the entire store. Two and a half hours after waiting in the parking lot, one of the firemen explained what had happened. Apparently one of our dumber co-workers, who had obviously had no knowledge of high school chemistry, had dumped ammonia and bleach down the drain of the food court. For those of you want to know, they combine to form cyanide gas. Needless to say, he was terminated shortly afterwards.