The attachment underneath most common office chairs used to raise or lower the chair's height, or when pulled out, to make whoever will sit in it next look like an idiot. When the lever is in, the occupant can recline to a reasonable distance. When this lever is pulled out however, the unwitting fool will recline way further than thought possible, causing this person to experience the feeling of falling. This may result in, but is not limited to: accelerated heart rate, loud outbursts of curse words, loss of colon control, and (according to a study I just made up) over 1000 heart attacks per year.
Frank: "Holy @$%#!"
Frank: "Who the hell pulled the heart attack lever out on my chair?!"
Alex: "Does something smell like zoo poo?"