I thought of this brilliant device today when my sister locked me and my friend in a storage room.
My friend lives in an apartment and has an underground corridor running through the storage rooms of the houses. We rigged the door from his room to the storage room so we could get in if it was locked. But we didn't think about rigging the door from the storage room to the corridor. So i thought of a few ways we could open the door and this was the simplest one.
I added a video because no one can figure this thing out apparently.