Turning the lights on

One time in my undergraduate university, a group of students wanted to make a huge banner in secret. The banner was so large, we had to unroll it down the hallway of our dorm. Needless to say, this resulted in a lot of questions. One guy got the brilliant idea of telling people that we were making a huge circuit, using pencil lead drawn on the paper as a conductor. This resulted in a large crowd of engineers arguing the logistics of running a circuit through pencil lead.