A chain lock is a common type of lock that is found in homes and hotel rooms. It consists of a chain that is connected to the wall and fits into a metal casing on the door. When the door is opened, the chain prevents anyone on the outside from coming in; it does not allow the door to open more than a couple of inches. Short of kicking down the door, there is only one way to open a chain lock from the outside, and only when some very specific conditions are met.
Hold the chain lock in your hands. Slide the chain away from the door frame.
Lift the chain out of the metal casing.
Open the door.
Open the door from the outside. You must be able to unlock any other locks that obstruct you.
Slip your hands through the door and wrap one end of the rubber band around the chain lock as close to the metal casing as possible. Pull it through the loop in the other end of the rubber band. Be sure the loose end of the rubber band can stretch to the door handle.
Stretch the long end of the rubber band over the end of the door handle.
Shut the door. The rubber band should pull the chain lock out of its casing.
Open the door to the room.