[Tony_P]

Here's an idea that I stole from somewhere, but I can't remember where. You need to have a room with a door that opens in. I did this in a stock room at my old job.

Lie down on the floor with your feet touching the door. Dump out a box of paper clips in front of your head. If someone comes in, the door will wake you (worked especially well for me b/c the door had a loud keypad lock) and you just hop to your knees and begin picking up the paperclips.