phalkor, from xkcd forums:

On a related note I find it funny how if you leave instructions somewhere people generally tend to obey them. At school I discovered a door that was locked but would grant roof access (8 story academic building). I really wanted to get to the roof (because why not?) so I went to print a piece of paper that said in caps "DO NOT LOCK THIS DOOR" and taped it to the door. Sure enough, the next day the door was found unlocked with the note still attached to it. Yay for obedience to anonymous commands!