You know how most people put a tie around their knob or a "Do Not Disturb" sign to ensure privacy? Well designer Arnaud Lapierre decided that wasn't enough, so he put together the Doorknob Condition, which is a doorknob that uses a pulley system to retract the entire doorknob, preventing anybody from getting in without breaking down the door. Although I still prefer my method of keeping people out: building the door out of a giant angry bear.

Check out more shots of this thing in action after the jump.

The Doorknob Signal [Yanko Design]