This instructable will show you how to temporarily lock a standard, internal door from inside or out, using a minimum of 4 feet of cord (and a padlock if you are locking the door from the outside) although for ease of use, a large paper clip and some sort of hook and a keyring can be added.
Step 1: Attach the cord to the door handle
Although this may seem simple enough, this is the hardest part of the project as the knot tends to slide along the handle to the pivot end when someone tries to turn the handle.
First, cut a length of cord aproximately 12"long and fold it in half, then tie a knot at the folded end, leaving a loop just big enough to fit the end of the door handle through. Place this over the handle with the knot at the bottom, then pull the two loose ends up over the little lumps on the end of the handle and tuck them under the top of the loop. put them back through the loop and pull upwards then the cord should be attached to the end of the handle.
If you are using a hook and a ring (inside lock only), tie the ring to the two bits of cord hanging off the top, otherwise, just tie a big knot that you can attach the second piece of cord (from the top of the door to)