Contestant #2

Now contestant #2's entry:

Picture this:

A doorknob with a string tied around it. String is looped around a pulley. When door is opened, the string pulls taut, which upsets a little bucket of ball bearings. The ball bearings pour into a vertically-placed pvc pipe which has been filled with water-based lube. The additional weight of the ball bearings causes a hinged cover on the distal end of the pvc pipe to swing open, releasing the lube-coated ball bearings onto the floor. At the same time, a match that has been taped to the top of the door scrapes against sandpaper which has been taped to the inside of the door frame. the match ignites a cup of silicon-based lube, which is upset by the door opening and spills onto the head of whoever is trying to open it. Flaming, arm-flailing chaos ensues. Most awesome burglar system ever!