The older I get, the smaller my cubicle gets. In fact, I don't even have a cubicle now. But my boss used to walk in undetected and catch me doing research for some assignment (WWW - to the boss it looked like web surfing) and he would tell me to get to work. I wanted to put a cowbell around him, but I'm sure he wouldn't go for it, so I had to come up with something else. (note - the title should be "Flatulent.")
Step 1: Picked up this nifty noise maker for about 6 bucks in the toy section of the food store.
You can read the package for yourself. It has about 6 different random "tunes." But, the key item is the little RF remote button that comes with it.
Step 2: And I found this little gem in WalMart for about $5.00.
Obviously it turns on a little light (LED) when motion is detected, and the room is dark. (Hmmmmm, I wonder if I could...)
Step 3: Okay. Let's crack open the motion sensor and have a look see...
Well, I labeled everything. The photocell (not shown, but trust me, it's there) is to prevent the light (LED) from coming on during the daytime, and therefore prolongs the battery life.
The Fresnel lens is there to provide a wide field-of view for the motion sensor. Fresnel is pronounced frie-nel, look it up on Wikipedia for more info.