Helped my once! It is also how drinking botteled water benefited my health.
I was living alone in Moscow in a rental apartment on a 15th floor with windows facing a noisy highway and behind a metal door (security) isolated so good that one could not hear though it (convenience).
One day I hooked up with a couple of girls …. and when I woke up I found myself alone locked in the apartment with without my keys, wallet, phone and laptop. They were stolen and the door was locked from outside. This kind of door can’t be opened from inside without a key when locked with the key (security again).
In other words - I was locked in my own apartment with no means of communication for indefinite amount of time - probably for weeks. Not a lot of fun.
Tap water in Moscow was not great and I was buying water in large plastic bottles. As the result, I had a stockpile of bottles.
Here the rescure plan came to my mind: I prepared a number of written messages, put them in the bottles and started to throw them one-by-one out of a window aiming at people passing by.
It worked - I few minutes later someone notices bombardment with plastics botteles, noticed a note inside, and a few hours later I was rescued.