Tv-B-Gone glove
I have had a great idea (by my standards anyway). Those in the geek world should know about the tv-b-gone created by Mitch Aldman. It is designed to turn off about 90% of televisions with a single button press. My plan is to take that idea and turn it into a glove for fun and games.
Implementation
Take a glove, preferably fabric and one that you do not mind potentially destroying. Push the legs of an infrared LED through the tip of the index finger. Sew/solder some conductive thread to it and thread through the glove to the back of the palm. Do the same with a micro switch on the thumb. Hook the threads into a Lilypad Arduino and secure the Lilypad to the back of the glove.
Usage
Wear some sort of cloak to make yourself look like a monk or a Bedouin. Walk into a store that has a wall of TVs. Point at the TV wall with your index finger, say something about TVs being evil and covertly press your thumb against your index finger. TVs should turn off and send people running scared due to the scary cloaked figure manipulating technology in an unknown way.
The only difficulties I foresee is getting the codes to turn off televisions and getting arrested. Aside from that, I figure this should be very fun and educational.